Recent Advances in Asymmetric [3,3]-Sigmatropic Rearrangements

Abstract

The synthesis of new complex structures is still a challenge in preparative organic chemistry. Focusing on the generation of defined stereogenic centers, the [3,3]-sigmatropic rearrangements are known as reliable reactions. Always, a highly ordered transition state must be passed through, which allows the shift of chiral information from the reactant into the nascent product. Generally, the complete [1,3]- and, frequently, the [1,4]-chirality transfer enables one to predict the configuration of the new centers.

This review focuses on Claisen and Cope rearrangements, which adopt the chiral information via a so termed asymmetric induction. This means, that the directing chiral subunit is placed outside of the six centers of the rearrangement system being reorganized during the course of the [3,3]-sigmatropic reaction.

Reviewing the literature since 1995, enantioselective Claisen rearrangements have been widely investigated. The unique sense of the reaction allows the conversion of an easily accessible C atom-heteroatom bond into a new C-C bond making this rearrangement useful for constructing complex molecules. In contrast, the Cope rearrangement is reversible. One crucial requirement is to force the process to completion with respect to the desired product. Hence ‘enantioselective Cope rearrangements’ are always included as one step in a reaction cascade to guarantee the unique sense of the process. Analyzing such reactions in more detail, the chirality-inducing step is run prior to the Cope rearrangement. Thus, the [3,3]-sigma­tropic rearrangement is conducted under the well-known [1,3]-chirality transfer conditions.

• 1 Introduction

• 2 Asymmetric Claisen Rearrangements: Classification

• 3 Remote Stereocontrol in Claisen Rearrangements

• 3.1 Stereogenic Center at C1

• 3.2 Stereogenic Center at C6

• 3.3 Stereogenic Center in Other Positions

• 4 Auxiliary Control in Claisen Rearrangements

• 4.1 Auxiliary Attached to Position X

• 4.2 Auxiliary Attached to Position Y

• 4.3 Auxiliary Attached to Position Z

• 4.4 Miscellaneous

• 5 Chiral Metal Complex Directed Claisen Rearrangements

• 6 Enantioselective Catalyzed Claisen Rearrangements

• 7 Asymmetric Cope Rearrangements

• 7.1 Remote Stereocontrol in Cope Rearrangements

• 7.2 Auxiliary Control in Cope Rearrangements

• 7.3 Catalyst Control in Cope Rearrangements

• 8 Summary

asymmetric Claisen rearrangement - Cope rearrangement - chiral auxiliary - chiral metal complex - chiral catalyst

References

For recent reviews on asymmetric Claisen and Cope rearrangements see:

1a Frauenrath H. In Houben-Weyl (Methods of Organic Chemistry), Stereoselective Synthesis   Vol. E21d:  Helmchen G. Hoffmann RW. Mulzer J. Schaumann E. Thieme; Stuttgart: 1995.  p.3301 

1b Metzner P. Pure Appl. Chem.  1996,  68:  863 

1c Enders D. Knopp M. Schiffers R. Tetrahedron: Asymmetry  1996,  7:  1847 

1d Ito H. Taguchi T. Chem. Soc. Rev.  1999,  28:  43 

1e Kazmaier U. Maier S. Zumpe FL. Synlett  2000,  1523 

1f Allin SM. Baird RD. Curr. Org. Chem.  2001,  395 

1g Hiersemann M. Abraham L. Eur. J. Org. Chem.  2002,  1461 

1h Chai Y. Hong S.-P. Lindsay HA. McFarland C. McIntosh MC. Tetrahedron  2002,  58:  2905 

1i Paquette LA. Tetrahedron  1997,  53:  1397 

For catalytic asymmetric reactions see:

2a Avalos M. Babiano R. Cintas P. Jiménez JL. Palacios JC. Tetrahedron: Asymmetry  1997,  8:  2997 

2b Brunel J.-M. Luukas TO. Kagan HB. Tetrahedron: Asymmetry  1998,  9:  1941 

2c Kolb HC. VanNieuwenhze MS. Sharpless KB. Chem. Rev.  1994,  94:  2483 

3a Palmer MJ. Wills M. Tetrahedron: Asymmetry  1999,  10:  2045 

3b Daviero P. Zanda M. Tetrahedron: Asymmetry  2001,  12:  2225 

4a Gotor V. Rebolledo F. Liz R. Tetrahedron: Asymmetry  2001,  12:  513 

4b Enzyme Catalyst in Organic Synthesis   Drauz K. Waldmann H. VCH; Weinheim, Germany: 1995. 

5 Sreekumar R. Padmakumar R. Tetrahedron Lett.  1997,  38:  2413 

6 Beslin P. Lelong B. Tetrahedron  1997,  53:  17253 

7 Cuzzupe AN. Di Florio R. Rizzacasa MA. J. Org. Chem.  2002,  67:  4392 

8a Pratt LM. Bowles SA. Courtney SF. Hidden C. Lewis CN. Martin FM. Todd RS. Synlett  1998,  531 

8b Pratt LM. Beckett RP. Bellamy CL. Corkill DJ. Cossins J. Courtney PF. Davies SJ. Davidson AH. Drummond AH. Helfrich K. Lewis CN. Mangan M. Martin FM. Miller K. Nayee P. Ricketts ML. Thomas W. Todd RS. Whittaker M. Bioorg. Med. Chem. Lett.  1998,  8:  1359 

9a Yamazaki T. Shinohara N. Kitazume T. Sato S. J. Org. Chem.  1995,  60:  8140 

9b Yamazaki T. Ichige T. Takei S. Kawashita S. Kitazume T. Kubota T. Org. Lett.  2001,  3:  2915 

9c For a publication concerning Michael additions see: Shinohara N. Haga J. Yamazaki T. Kitazume T. Nakamura S. J. Org. Chem.  1995,  60:  4363 

9d For the Cieplack model see: Cieplak AS. Chem. Rev.  1999,  99:  1265 

9e For a publication on racemic Michael-Ireland sequences see: Eriksson M. Hjelmencrantz A. Nilsson M. Olsson T. Tetrahedron  1995,  51:  12631 

10 Hagiwara H. Sakai H. Uchiyama T. Ito Y. Morita N. Hoshi T. Suzuki T. Ando M. J. Chem. Soc., Perkin Trans. 1  2002,  583 

11 Becker M. Krause N. Liebigs Ann. Recueil  1997,  725 

12a Alayrac C. Fromont C. Metzner P. Anh NT. Angew. Chem., Int. Ed. Engl.  1997,  36:  371 ; Angew. Chem. 1997, 109, 418

12b Nowaczyk S. Alayrac C. Reboul V. Metzner P. Averbuch-Pouchot M.-T. J. Org. Chem.  2001,  66:  7841 

12c For preparation of optically active sulfoxides see: Alayrac C. Nowaczyk S. Lemarie M. Metzner P. Synthesis  1999,  669 

12d Alayrac C. Metzner P. Tetrahedron Lett.  2000,  41:  2537 

13a Ernst B. Gonda J. Jeschke R. Nubbemeyer U. Öhrlein R. Bellus D. Helv. Chim. Acta  1997,  80:  876 

13b Gonda J. Martinková M. Ernst B. Bellus D. Tetrahedron  2001,  57:  5607 

13c For a preliminary publication see: Nubbemeyer U. Öhrlein R. Gonda J. Ernst B. Bellus D. Angew. Chem., Int. Ed Engl.  1991,  30:  1465 ; Angew. Chem. 1991, 103, 1533

14a Nubbemeyer U. J. Org. Chem.  1995,  60:  3773 

14b Nubbemeyer U. J. Org. Chem.  1996,  61:  3677 

14c Laabs S. Scherrmann A. Sudau A. Diederich M. Kierig C. Nubbemeyer U. Synlett  1999,  25 

15a von Braun J. Chem. Ber.  1907,  40:  3914 

15b Cooley JH. Evain EJ. Synthesis  1989,  1 

16 Mulzer J. Shanyoor M. Tetrahedron Lett.  1993,  34:  6545 

17a Martinková M. Gonda J. Tetrahedron Lett.  1997,  38:  875 

17b Gonda J. Bednarikova M. Tetrahedron Lett.  1997,  38:  5569 

17c Gonda J. Martinková M. Walko M. Zavacká E. Milos¡ Bud ínsk M. Ivana Císaová I. Tetrahedron Lett.  2001,  42:  4401 

17d Gonda J. Martinková M. Imrich J. Tetrahedron  2002,  58:  1611 

A Johnson rearrangement involving such a system was found to be unselective:

18a Tadano K. Idogaki Y. Yamada H. Suami T. Chem Lett.  1985,  1925 

18b Tadano K. Idogaki Y. Yamada H. Suami T. J. Org. Chem.  1987,  52:  1201 

19a Gonda J. Zavacka E. Budesinsky M. Cisarova I. Podlaha J. Tetrahedron Lett.  2000,  41:  525 

19b Gonda J. Helland A.-C. Ernst B. Bellus D. Synthesis  1993,  729 

20 Overman LE. Angew. Chem., Int Ed. Engl.  1984,  23:  579 ; Angew. Chem. 1984, 96, 565

21

For the discussion of a stepwise reaction mechanism see chapter 6 and the literature cited therein.

22a Ovaa H. Codee JDC. Lastdrager B. Overkleeft HS. van der Marel GA. van Boom JH. Tetrahedron Lett.  1999,  40:  5063 

22b Nishikawa T. Asai M. Ohyabu N. Yamamoto N. Fukuda Y. Isobe M. Tetrahedron  2001,  57:  3875 

22c Nishikawa T. Asai M. Isobe M. J. Am. Chem. Soc.  2002,  124:  7847 

23a Boeckman RK. Neeb MJ. Gaul MD. Tetrahedron Lett.  1995,  36:  803 

23b Boeckman RK. del Rosario Rico Ferreira M. Mitchell LH. Shao P. J. Am. Chem. Soc.  2002,  124: 

24 Magnus P. Westwood N. Tetrahedron Lett.  1999,  40:  4659 

25 Fukuzaki T. Kobayashi S. Hibi T. Ikuma Y. Ishihara J. Kanoh N. Murai A. Org. Lett.  2002,  4:  2877 ; further racemic examples of model compound rearrangements are given in this reference

26 Barrett AGM. Ahmed M. Baker SP. Baugh SPD. Braddock DC. Procopiou PA. White AJP. Williams DJ. J. Org. Chem.  2000,  65:  3716 

27a Vourloumis D. Kim KD. Petersen JL. Magriotis PA. J. Org. Chem.  1996,  61:  4848 

27b For a preliminary communication see: Magriotis PA. Kim KD. J. Am. Chem. Soc.  1993,  115:  2972 

28 de la Pradilla RF. Montero C. Tortosa M. Org. Lett.  2002,  4:  2373 

29a Tsunoda T. Nishii T. Yoshizuka M. Yamasaki C. Suzuki T. Itô S. Tetrahedron Lett.  2000,  41:  7667 

29b For preliminary publications see: Tsunoda T. Sakai M. Sasaki O. Sako Y. Hondo Y. Tetrahedron Lett.  1992,  33:  1651 

29c Tsunoda T. Tatsuki S. Shiraishi Y. Akasaka M. Itô S. Tetrahedron Lett.  1993,  34:  3297 

29d Tsunoda T. Tatsuki S. Kataoka K. Itô S. Chem. Lett.  1994,  543 

29e Itô S. Tsunoda T. Pure Appl. Chem.  1994,  66:  2071 

29f Tsunoda T. Ozaki F. Shirakata N. Tamaoka Y. Yamamoto H. Itô S. Tetrahedron Lett.  1996,  37:  2463 

30a Laabs S. Münch W. Bats J.-W. Nubbemeyer U. Tetrahedron  2002,  58:  1317 

30b Zhang N. Nubbemeyer U. Synthesis  2002,  242 ; for a preliminary result see ref. 14c

31

The Ireland-type rearrangements are characterized by metal enolates bearing chiral ligands. These reactions are discussed in chapter 5 (vide infra).

32a Mulder JA. Hsung RP. Frederick MO. Tracey MR. Zificsak CA. Org. Lett.  2002,  4:  1383 

32b For a synthesis of alkynyl amides see: Wei L.-L. Mulder JA. Xiong H. Zificsak CA. Douglas CA. Hsung RP. Tetrahedron  2001,  57:  459 

33a Sibi auxiliary: Sibi MP. Porter NA. Acc. Chem. Res.  1999,  32:  163 

33b Evans asymmetric aldol reaction: Evans DA. Aldrichimica Acta  1982,  15:  23 

34a Hungerhoff B. Metz P. Tetrahedron  1999,  55:  14941 

34b Hungerhoff B. Metz P. J. Org. Chem.  1997,  62:  4442 

34c Hungerhoff B. Metz P. GIT Fachz. Lab.  1996,  40:  690 

35 Metz P. Tetrahedron  1993,  49:  6367 

36a Welch JT. Eswarakrishnan S. J. Am. Chem. Soc.  1987,  109:  6716 

36b Reddy KV. Rajappa S. Tetrahedron Lett.  1992,  33:  7957 

36c Jain S. Sinha N. Dikshit DK. Anand N. Tetrahedron Lett.  1995,  36:  8467 

37a Lemieux RM. Meyers AI. J. Am. Chem. Soc.  1998,  120:  5453 

37b Lemieux RM. Devine PM. Mechelke MF. Meyers AI. J. Org. Chem.  1999,  64:  3585 

37c Watson DJ. Lawrence CM. Meyers AI. Tetrahedron Lett.  2000,  41:  815 

37d For a preliminary publication see: Devine PM. Meyers AI. J. Am. Chem. Soc.  1994,  116:  2633 

37e For a palladium-catalyzed rearrangement (moderate stereoselectivity): Watson DJ. Devine PM. Meyers AI. Tetrahedron Lett.  2000,  41:  1363 

38

The reversibility had been proven by subjecting the pure product to the reaction conditions resulting in the Claisen reactant and potentially some other diastereomers.

39 Wilkens J. Wallbaum S. Saak W. Haase D. Pohl S. Patkar LN. Dixit AN. Chittari P. Rajappa S. Martens J. Liebigs Ann.  1996,  927 

40 He S. Kozmin SA. Rawal VH. J. Am. Chem. Soc.  2000,  122:  190 ; additionally the commercially available C₂-symmetric 2,5-bis-(methoxymethyl) pyrrolidine had been employed once resulting in a high yield and a high diastereoselectivity

41 Dantale S. Reboul V. Metzner P. Philouze C. Chem.-Eur. J.  2002,  8:  632 

42a Kallmerten J. Gould TJ. J. Org. Chem.  1986,  51:  1152 

42b For another chelate controlled racemic ester enolate Claisen rearrangement see: Krafft ME. Dasse OA. Jarrett S. Fievre A. J. Org. Chem.  1995,  60:  5093 

43a Maier S. Kazmaier U. Eur. J. Org. Chem.  2000,  1241 

43b Kazmaier U. J. Org. Chem.  1994,  59:  6667 

44a Enders D. Knopp M. Tetrahedron  1996,  52:  5805 

44b Enders D. Knopp M. Runsink J. Raabe G. Liebigs Ann.  1996,  1095 

44c Enders D. Knopp M. Runsink J. Raabe G. Angew. Chem., Int. Ed. Engl.  1995,  34:  2278 ; Angew. Chem. 1995, 107, 2442

45a Dalko PI. Langlois Y. Tetrahedron Lett.  1998,  39:  2107 

45b For a review concerning related rearrangements see: Kelly TR. Arvanitis A. Tetrahedron Lett.  1984,  25:  39 

46 Roush WR. Works AB. Tetrahedron Lett.  1997,  38:  351 

47a Maruoka K. Saito S. Yamamoto H. J. Am. Chem. Soc.  1995,  117:  1165 

47b Racemic catalytic variant: Saito S. Shimada K. Yamamoto H. Synlett  1996,  720 

47c For some early publications see: Maruoka K. Banno H. Yamamoto H. J. Am. Chem. Soc.  1990,  112:  7791 

47d Maruoka K. Yamamoto H. Tetrahedron: Asymmetry  1991,  2:  647 

47e Maruoka K. Yamamoto H. Synlett  1991,  793 

48 For an early publication using a (IPC)₂BOTf: Oh T. Wrobel Z. Devine PN. Synlett  1992,  81 

49 Tayama E. Saito A. Ooi T. Maruoka K. Tetrahedron  2002,  58:  8307 

50a Corey EJ. Kania RS. J. Am. Chem. Soc.  1996,  118:  1229 

50b Corey EJ. Roberts BE. Dixon BR. J. Am. Chem. Soc.  1995,  117:  193 

51

The use of Hünig’s base resulted in a disappointing yield of only 36%. Barton’s base: pentaisopropylguanidine.

52a Ito H. Sato A. Kobayashi T. Taguchi T. J. Chem. Soc., Chem. Commun.  1998,  2441 

52b Ito H. Sato A. Taguchi T. Tetrahedron Lett.  1997,  38:  4815 

53

The boron ester formation was crucial for the Claisen rearrangement to proceed. In the absence of an o-OH group the reaction failed. The o-OH group could be replaced by a carboxylic acid function but such conversion resulted a lower yield and a decreased enantioselectivity. Additionally some p-product was isolated.

54a Kazmaier U. Mues H. Krebs A. Chem.-Eur. J.  2002,  8:  1850 

54b Mues H. Kazmaier U. Synthesis  2001,  487 

54c Mues H. Kazmaier U. Synlett  2000,  1004 

54d Bakke M. Ohta H. Kazmaier U. Sugai T. Synthesis  1999,  1671 

54e Krebs A. Kazmaier U. Tetrahedron Lett.  1999,  40:  479 

54f Krebs A. Kazmaier U. Tetrahedron Lett.  1996,  37:  7945 

54g Kazmaier U. Krebs A. Angew. Chem., Int. Ed. Engl.  1995,  34:  2012 ; Angew. Chem. 1995, 107, 2213

54h Kazmaier U. Maier S. J. Chem. Soc., Chem. Commun.  1995,  1991 

55 Yoon TP. MacMillan DWC. J. Am. Chem. Soc.  2001,  123:  2911 

56

However this special variant did obviously not suffer from any von Braun type degradation or from any [2+2]-cycloadditions as reported in previous publications and references cited therein).

For potential catalysts see

57a Helmchen G. Pfaltz A. Acc. Chem. Res.  2000,  33:  336 

57b Fache F. Schulz E. Tommasino ML. Lemaire M. Chem. Rev.  2000,  100:  2159 

58a Sugiura M. Nakai T. Tetrahedron Lett.  1996,  37:  7991 

58b Sugiura M. Yanagisawa M. Nakai T. Synlett  1995,  447 

59

Reacting non-symmetric enol ethers the palladium-catalyzed version preferentially gave the less-substituted vinyl systems. The rearrangement passed through a boat-like transition state. In contrast the proton-catalyzed reaction gave the higher substituted vinylether and the thermal rearrangement (100 °C) passed through a chair-like transition state. Regio- and stereochemistry could be influenced by a careful choice of the reaction conditions. For the discussion of a two-step reaction mechanism see Overman amidate rearrangements. [67]

60a Trost BM. Schroeder GM. J. Am. Chem. Soc.  2000,  122:  3785 

60b Trost BM. Toste DF. J. Am. Chem. Soc.  1998,  120:  815 

60c For a racemic version see: Gester S. Metz P. Zierau O. Vollmer G. Tetrahedron  2001,  57:  1015 

60d For a potential racemization during aromatic Claisen rearrangements see: Bernard AM. Cocco MT. Onnis V. Piras PP. Synthesis  1997,  41 

Generally such intermediate cations could suffer from so-called abnormal 1,3 Claisen rearrangements. A catalytic variant to generate polycyclic terpenoids has been investigated by:

61a Nakamura S. Ishihara K. Yamamoto H. J. Am. Chem. Soc.  2000,  122:  8131 

61b For further 1,3 rearrangements (chirality transfer) see: Shiina I. Nagasue H. Tetrahedron Lett.  2002,  43:  5837 

61c See also: Hashimoto H. Jin T. Karikomi M. Seki K. Hagaa K. Uyeharaa T. Tetrahedron Lett.  2002,  43:  3633 

62a Wood JL. Moniz GA. Org. Lett.  1999,  1:  371 

62b Drutu I. Krygowski ES. Wood JL. J. Org. Chem.  2001,  66:  7025 

62c For a direct allylation of diazoketones as a surrogate for catalyzed enantioselective Claisen rearrangements see: Davies HML. Ren P. Jin Q. Org. Lett.  2001,  3:  3587 

63

The rhodium catalyst did not influence the Claisen rearrangement step.

64a Miller SP. Morken JP. Org. Lett.  2002,  4:  2743 

64b For further tandem processes see: Diels-Alder/Claisen: Soldermann N. Velker J. Vallat O. Stoeckli-Evans H. Neier R. Helv. Chim. Acta  2000,  83:  2266 

64c Frank SA. Works AB. Roush WR. Can. J. Chem.  2000,  78:  757 

65a Wipf P. Ribe S. Org. Lett.  2001,  3:  1503 

65b

The Claisen rearrangement is an ideal precursor for olefin converting consecutive processes such as metathesis dihydroxylations etc.

66a Abraham L. Czerwonka R. Hiersemann M. Angew. Chem. Int. Ed.  2001,  40:  4700 ; Angew. Chem. 2001, 113, 4835

66b For catalyzed racemic rearrangements see: Hiersemann M. Abraham L. Org. Lett.  2001,  3:  49 

66c Hiersemann M. Synthesis  2000,  1279 

66d Kaden S. Hiersemann M. Synlett  2002,  1999 

67a Calter M. Hollis TK. Overman LE. Ziller J. Zipp GG. J. Org. Chem.  1997,  62:  1449 

67b Kollis TK. Overman LE. Tetrahedron Lett.  1997,  38:  8837 

67c Cohen F. Overman LE. Tetrahedron: Asymmetry  1998,  9:  3213 

67d Donde Y. Overman LE. J. Am. Chem. Soc.  1999,  121:  2933 

67e For the thermal and palladium-catalyzed racemic rearrangement see: Overman LE. Zipp GG. J. Am. Chem. Soc.  1997,  62:  2288 

68 Kang J. Yew KH. Kim TH. Choi DH. Tetrahedron Lett.  2002,  43:  9509 

69a Jiang Y. Lougmire JM. Zhang X. Tetrahedron Lett.  1999,  40:  1449 

69b Leung P.-H. Ng K.-H. Li Y. White AJP. Williams DJ. J. Chem. Soc., Chem. Commun.  1999,  2435 

69c Uozumi Y. Kato K. Hayashi T. Tetrahedron: Asymmetry  1998,  9:  1065 

70 Gais H.-J. Böhme A. J. Org. Chem.  2002,  67:  1153 

For an aza-Cope-Mannich tandem process see:

71a Knight SD. Overman LE. Pairaudeau G. J. Am. Chem. Soc.  1995,  117:  5776 

71b

For oxy-Cope-aldol tandem process see ref. [1i]

72 Low stereoselectivities were observed in several anionic oxy-Cope rearrangements: Lee Y. Lee YR. Moon O. Kwon O. Shim MS. Yun JS. J. Org. Chem.  1994,  59:  1444 

For an example where a chiral chromium arene complex did not affect the stereochemical outcome of a Cope rearrangement see:

73a Mandal SK. Sarkar A. J. Chem. Soc., Perkin Trans. 1  2002,  669 

73b For an aza-Cope rearrangement via chromium carbene complexes see: Barluenga J. Tomas M. Ballesteros A. Santamaria J. Suarez-Sobrino A. J. Org. Chem.  1997,  62:  9229 

74a Kuehne ME. Xu F. J. Org. Chem.  1997,  62:  7950 

74b Kuehne ME. Xu F. J. Org. Chem.  1998,  63:  9427 

74c Kuehne ME. Xu F. J. Org. Chem.  1998,  63:  9434 

75 Deloisy S. Kunz H. Tetrahedron Lett.  1998,  39:  791 

76a Cardoso AS. Lobo AM. Prabhakar S. Tetrahedron Lett.  2000,  41:  3611 

76b Depew KM. Danishefsky SJ. Rosen N. Sepp-Lorenzino L. J. Am. Chem. Soc.  1996,  118:  12463 

77

The 3,5-rearrangement can be described as an iminium salt olefin addition and a subsequent fragmentation (cation stabilization). No new stereogenic center was constructed.

78 Román E. Baños M. Higes FJ. Serrano JA. Tetrahedron: Asymmetry  1998,  9:  449 

79 Agami C. Couty F. Puchot-Kadouri C. Synlett  1998,  449 

80a Nokami J. Ohga M. Nakamoto H. Matsubara T. Hussain I. Kataoka K. J. Am. Chem. Soc.  2002,  123:  9168 

80b For preliminary publications see: Nokami J. Anthony L. Sumida S. Chem.-Eur. J.  2000,  6:  2909 ; concept

80c See also: Sumida S. Ohga M. Mitani J. Nokami J. J. Am. Chem. Soc.  2000,  122:  1310 

80d Nokami J. Yoshizane K. Matsuura H. Sumida S. J. Am. Chem. Soc.  1998,  120:  6609 

80e Semeyn C. Blaauw RH. Hiemstra H. Speckamp WN. J. Org. Chem.  1997,  62:  3426 

80f For a recent publication (1,3 chirality transfer in 2-oxonia Cope rearrangements see: Loh T.-P. Hu Q.-Y. Ma L.-T. Org. Lett.  2002,  4:  2389 

The reversibility of the Cope rearrangement might cause some racemization - the avoiding of such a process was recommended. Alternatively a Prins cyclization could be discussed as the basic reaction mechanism. Cope rearrangements were found to be much faster than the Prins reaction. For the role of oxonia Cope rearrangements in Prins cyclizations see:

81a Rychnovsky SD. Marumoto S. Jaber JJ. Org. Lett.  2001,  3:  3815 

81b Marumoto S. Jaber JJ. Vitale JP. Rychnovsky SD. Org. Lett.  2002,  4:  3919 

82a Allin SM. Baird RD. Lins RJ. Tetrahedron Lett.  2002,  43:  4195 

82b Allin SM. Button MAC. Baird RD. Synlett  1998,  1117 

82c Allin SM. Button MAC. Tetrahedron Lett.  1998,  39:  3345-3348  

82d For preliminary publications see: Allin SM. Button MAC. Shuttleworth SJ. Synlett  1997,  725 

83

n-BuLi was found to be the base of choice to induce the anionic amino Cope rearrangements. Experiments using alternative strong bases such as LDA and KHMDS failed.

84a Young Yoo H. Houk KN. Lee JK. Scialdone MA. Meyers AI. J. Am. Chem. Soc.  1998,  120:  205 

84b Dobson HK. LeBlanc R. Perrier H. Stephenson C. Welch TR. Macdonald D. Tetrahedron Lett.  1999,  40:  3119 

84c Allin SM. Button MAC. Tetrahedron Lett.  1999,  40:  3801 

85 Tomooka K. Nagasawa A. Wei S.-Y. Nakai T. Tetrahedron Lett.  1996,  37:  8899 

86

In contrast to the Oppolzer sultams the corresponding Evans auxiliary gave only moderate chiral induction of about 50% de building-up the new stereogenic center.

87 Tomooka K. Nagasawa A. Wei S.-Y. Nakai T. Tetrahedron Lett.  1996,  37:  8995 

88a Schneider C. Rehfeuter M. Tetrahedron Lett.  1998,  39:  9 

88b Black WC. Giroux A. Greidanus G. Tetrahedron Lett.  1996,  37:  4471 

89 Paquette LA. Tae J. J. Org. Chem.  1998,  63:  2022 

90 Davies HML. Ahmed G. Churchill MR. J. Am. Chem. Soc.  1996,  118:  10774 

For potential catalysts see:

91a Helmchen G. Pfaltz A. Acc. Chem. Res.  2000,  33:  336 

91b Fache F. Schulz E. Tommasino ML. Lemaire M. Chem. Rev.  2000,  100:  2159 

92a Davies HWL. Hodges ML. J. Org. Chem.  2002,  65:  5683 

92b Davies HML. Doan BD. J. Org. Chem.  1999,  64:  8501 

92c Davies HML. Stafford DG. Doan BD. Houser JH. J. Am. Chem. Soc.  1998,  120:  3326 

92d Davies HML. Doan BD. Tetrahedron Lett.  1996,  37:  3967 

92e For a racemic series synthesizing azabicyclo[3,2,2]nonanes see: Davies HML. Hodges LM. Thornley CT. Tetrahedron Lett.  1998,  39:  2707 

92f Syntheses of tremulenolides: Davies HML. Doan BD. J. Org. Chem.  1998,  63:  657 

93

For a mechanistic discussion concerning the stereochemical outcome of the asymmetric catalyzed cyclopropanation see the original references.

94 Claisen L. Ber. Dtsch. Chem. Ges.  1912,  45:  1423 

95a Cope AC. Hardy EM. J. Am. Chem. Soc.  1940,  62:  441 

95b Cope AC. Hoyle KE. Heyl D. J. Am. Chem. Soc.  1941,  63:  1843 

95c Cope AC. Hofmann CM. Hardy EM. J. Am. Chem. Soc.  1941,  63:  1852 

95d Cope AC. Field L. J. Am. Chem. Soc.  1949,  71:  1589 

95e Whyte DE. Cope AC. J. Am. Chem. Soc.  1943,  65:  1999 

96a Carroll MF. J. Chem. Soc.  1940,  704 

96b Carroll MF. J. Chem. Soc.  1940,  1266 

96c Carroll MF. J. Chem. Soc.  1941,  507 

96d Wick AE. Felix D. Steen K. Eschenmoser A. Helv. Chim. Acta  1964,  47:  2425 

96e Wick AE. Felix D. Gschwend-Steen K. Eschenmoser A. Helv. Chim. Acta  1969,  52:  1030 

96f Johnson WS. Werthemann L. Bartlett WR. Brocksom TJ. Li TT. Faulkner DJ. Peterson MR. J. Am. Chem. Soc.  1970,  92:  741 

96g Ireland RE. Mueller RH. J. Am. Chem. Soc.  1972,  94:  5897 

96h Ireland RE. Willard AK. Tetrahedron Lett.  1975,  16:  3975 

96i Ireland RE. Mueller RH. Willard AK. J. Am. Chem. Soc.  1976,  98:  2868 

96j Baldwin JE. Walker JA. J. Chem. Soc., Chem. Commun.  1973,  117 

96k Greuter H. Lang RW. Romann AJ. Tetrahedron Lett.  1988,  29:  3291 

96l Malherbe R. Bellus D. Helv. Chim. Acta  1978,  61:  3096 

96m Denmark SE. Harmata MA. J. Am. Chem. Soc.  1982,  104:  4972 

96n Denmark SE. Harmata MA. J. Org. Chem.  1983,  48:  3369 

96o Denmark SE. Harmata MA. Tetrahedron Lett.  1984,  25:  1543 

96p Bergmann E. Corte H. J. Chem. Soc.  1935,  1363 

96q Lauer WM. Kilburn EI. J. Am. Chem. Soc.  1937,  59:  2586 

96r Hurd CD. Pollack MA. J. Am. Chem. Soc.  1938,  60:  1905 

96s Hurd CD. Pollack MA. J. Org. Chem.  1939,  4:  550 

96t Arnold RT. Searles S. J. Am. Chem. Soc.  1949,  71:  1150 

96u Arnold RT. Parham WE. Dodson RM. J. Am. Chem. Soc.  1949,  71:  2439 

96v Burgstrahler AW. Nordin IC. J. Am. Chem. Soc.  1961,  83:  198 

96w Marbet R. Saucy G. Helv. Chim. Acta  1967,  50:  2091 

97a Fehr C. Galindo JA. Angew. Chem. Int. Ed.  2000,  39:  569 ; Angew. Chem. 2000, 112, 581

97b Hong JH. Gao M.-Y. Choi Y. Cheng Y.-C. Schinazi RF. Chu CK. Carbohydr. Res.  2000,  328:  37 

97c Agami C. Couty F. Evano G. Eur. J. Org. Chem.  2002,  29 

97d Görth FC. Umland A. Brückner R. Eur. J. Org. Chem.  1998,  1055 

97e Brenna E. Fuganti C. Grasselli P. Serra S. Eur. J. Org. Chem.  2001,  1349 

97f Trost BM. Lee CB. J. Am. Chem. Soc.  2001,  123:  3687 

97g Corey EJ. Guzman-Perez A. Lazerwith SE. J. Am. Chem. Soc.  1997,  119:  11769 

97h Wood JL. Moniz GA. Pflum DA. Stoltz BM. Holubec AA. Dietrich HJ. J. Am. Chem. Soc.  1999,  121:  1748 

97i He F. Bo Y. Altom JD. Corey EJ. J. Am. Chem. Soc.  1999,  121:  6771 

97j Hodgson DM. Gibbs AR. Drew MGD. J. Chem. Soc., Perkin Trans. 1  1999,  3579 

97k Morimoto Y. Takaishi M. Kinoshita T. Sakaguchi K. Shibata K. J. Chem. Soc., Chem. Commun.  2002,  42 

97l Goujon J.-Y. Duval A. Kirschleger B. J. Chem. Soc., Perkin Trans. 1  2002,  496 

97m Roulland E. Monneret C. Florent J.-C. J. Org. Chem.  2002,  67:  4399 

97n Angle SR. Henry RM. J. Org. Chem.  1998,  63:  7490 

97o Burke SD. Sametz GM. Org. Lett.  1999,  1:  71 

97p Mapp AK. Heathcock CH. J. Org. Chem.  1999,  64:  23 

97q Hodgson DM. Gibbs AR. Synlett  1997,  657 

97r Harrison JR. Holmes AB. Collins I. Synlett  1999,  972 

97s Schaus JV. Jain N. Panek JS. Tetrahedron  2000,  56:  10263 

97t Chandrasekhar S. Venkat Reddy M. Tetrahedron  2000,  56:  6339 

97u Brenna E. Caraccia N. Fuganti F. Fuganti D. Grasselli P. Tetrahedron: Asymmetry  1997,  8:  3801 

97v Amat M. Dolors Coil M. Passarella D. Bosch J. Tetrahedron: Asymmetry  1997,  8:  2775 

97w Konno T. Kitazume T. Tetrahedron: Asymmetry  1997,  8:  223 

97x Guz NR. Lorenz P. Stermitz FR. Tetrahedron Lett.  2001,  42:  6491 

97y Zhou B. Edmondson S. Padron J. Danishefsky SJ. Tetrahedron Lett.  2000,  41:  2039 

97z Ceccarelli S. Piarulli U. Gennari C. Tetrahedron Lett.  1999,  40:  153 

98a Kazmaier U. Schneider C. Tetrahedron Lett.  1998,  39:  817 

98b Rutherford AP. Hartley RC. Tetrahedron Lett.  2000,  41:  737 

98c Paquette LA. Gao Z. Ni Z. Smith GF. Tetrahedron Lett.  1997,  38:  1271 

98d Paquette LA. Backhaus D. Braun R. Underiner TL. Fuchs K. J. Am. Chem. Soc.  1997,  119:  9662 

98e Martnez AG. Vilar ET. Fraile AG. Moya Cerero S. Maroto BL. Tetrahedron: Asymmetry  2002,  13:  17 

98f Bonjoch J. Sole D. Chem. Rev.  2000,  100:  3455 

98g Koch G. Janser P. Kottirsch G. Romero-Giron E. Tetrahedron Lett.  2002,  43:  4837 

98h Chen YK. Lurain AE. Walsh PJ. J. Am. Chem. Soc.  2002,  124:  12225 

98i Hatcher MA. Posner GH. Tetrahedron Lett.  2002,  43:  5009 

98j Srikrishna A. Anebouselvy K. Tetrahedron Lett.  2002,  3:  2769