Highly Regio- and Stereoselective Hydrostannylation of Propargyl Alcohols and Ethers Using Dibutylchlorostannane and Lithium Chloride

Abstract

In the presence of LiCl, dibutylchlorostannane (Bu₂SnClH) reacted with γ-unsubstituted propargyl alcohols and ethers to give γ-stannylated allyl alcohols and ethers, respectively, with high regio- and stereoselectivity. These vinylstannane products could be successfully utilized for the Pd-catalyzed cross-coupling reaction.

alcohols - alkynes - cross-coupling - hydrostannations - radical reactions

References

1a Davies AG. Organotin Chemistry   Wiley-VCH; Weinheim: 2004. 

1b Kosugi M. Fugami K. In Handbook of Organopalladium Chemistry for Organic Synthesis   Vol. 1:  Negishi E. Wiley; New York: 2002.  Chap. III.2.3. p.263 

1c Mitchell TN. In Metal-Catalyzed Cross-Coupling Reactions   Diederich F. Stang PJ. Wiley-VCH; Weinheim: 1998.  Chap. 4. p.167 

1d Pereyre M. Quintard J.-P. Rahm A. Tin in Organic Synthesis   Butterworths; London: 1987. 

1e Stille JK. Angew Chem., Int. Ed. Engl.  1986,  25:  508 

2a Davies AG. In Comprehensive Organometallic Chemistry II   Vol. 2:  Abel EW. Stone FGA. Wilkinson G. Pergamon; Oxford, UK: 1995.  p.217 

2b Kupchik EJ. In Organotin Compounds   Vol. 1:  Sawyer AK. Dekker; New York: 1971.  Chap. 2. p.7 

3a Leusink AJ. Budding HA. J. Organomet. Chem.  1968,  11:  533 

3b Nozaki K. Oshima K. Utimoto K. J. Am. Chem. Soc.  1987,  109:  2547 

3c Mitchell TN. Amamria A. J. Organomet. Chem.  1983,  252:  47 

3d Nakamura E. Imanishi Y. Machii D. J. Org. Chem.  1994,  59:  8178 

4a Ichinose Y. Oda H. Oshima K. Utimoto K. Bull. Chem. Soc. Jpn.  1987,  60:  3468 

4b Zhang HX. Guibé F. Balavoine G. J. Org. Chem.  1990,  55:  1857 

4c Betzer J.-F. Delaloge F. Muller B. Pancrazi A. Prunet J. J. Org. Chem.  1997,  62:  7768 

4d Mitchell TN. Moschref S.-N. Synlett  1999,  1259 

4e Smith ND. Mancuso J. Lautens M. Chem. Rev.  2000,  100:  3257 ; and references therein

5 Asao N. Liu J.-X. Sudoh T. Yamamoto Y. J. Chem. Soc., Chem. Commun.  1995,  2405 

6 Shibata I. Suwa T. Ryu K. Baba A. J. Am. Chem. Soc.  2001,  123:  4101 

7 Miura K. Wang D. Matsumoto Y. Fujisawa N. Hosomi A. J. Org. Chem.  2003,  68:  8730 

8 For a related work by us, see: Miura K. Saito H. Uchinokura S. Hosomi A. Chem. Lett.  1999,  659 

Quite recently, Mitchell et al. have reported results similar to those reported previously by us. See:

9a Thiele CM. Mitchell TN. Eur. J. Org. Chem.  2004,  337 

9b Highly regio- and stereoselective hydrostannylation of γ-unsubstituted propargyl ethers with Bu₂SnClH was also reported by them; however, the high regioselectivity could not be reproduced by our hands. See: Mitchell TN. Moschref S.-N. Chem. Commun.  1998,  1201 

10

For the Et₃B-initiated reaction, see ref. [3b]

11a Gallagher WP. Terstiege I. Maleczka RE. J. Am. Chem. Soc.  2001,  123:  3194 

11b Maleczka RE. Gallagher WP. Org. Lett.  2001,  3:  4173 

11c Maleczka RE. Gallagher WP. Terstiege I. J. Am. Chem. Soc.  2000,  122:  384 

11d Maleczka RE. Lavis JM. Clark DH. Gallagher WP. Org. Lett.  2000,  2:  3655 

12a Neumann WP. Pedain J. Tetrahedron Lett.  1964,  2461 

12b Davies AG. Kinart WJ. Osei-Kissi DK. J. Organomet. Chem.  1994,  474:  C11 

13

General Procedure for the Hydrostannylation of 1 with Bu ₂ SnClH-LiCl Followed by Butylation:
Under N₂, THF (1 mL) was added to a mixture of Bu₂SnCl₂ (83.5 mg, 0.275 mmol) and LiCl (21.2 mg, 0.500 mmol) at 0 °C. Bu₂SnH₂ (64.6 mg, 0.275 mmol) was added to the THF solution, and the mixture was stirred for 10 min at 0 °C. A propargyl alcohol 1 (0.500 mmol) was added to the resultant Bu₂SnClH-LiCl solution. The mixture was warmed to r.t. and stirred for 3 h. The resultant mixture was cooled to 0 °C and treated with BuMgBr (1.00 M in Et₂O, 1.30 mmol). After 20 min, the resultant mixture was poured into a 1:1 mixture of sat. aq NH₄Cl and H₂O. The extract with
t-BuOMe was dried over Na₂SO₄ and evaporated. Purification of the residual oil was performed by silica gel column chromatography (hexane-t-BuOMe 20:1).

γ-Substituted propargyl alcohols are known to undergo β-regioselective hydrostannylation with Bu₃SnH in the presence of a radical initiator. See:

14a Ensley HE. Buescher RR. Lee K. J. Org. Chem.  1982,  47:  404 

14b Konoike T. Araki Y. Tetrahedron Lett.  1992,  33:  5093 

15 The ¹¹⁹Sn signal of Bu₂SnClH (8 mmol in 1 mL of THF-d ₈) was reported to appear at δ = -18.3 ppm. See: Kawakami T. Sugimoto T. Shibata I. Baba A. Matsuda H. Sonoda N. J. Org. Chem.  1995,  60:  2677 

Shibata and Baba et al. have reported that halide ions and HMPA easily complex Bu₂SnXH (X = F, Cl, Br, I), and that the resulting 5-coordinate tin compounds can be successfully used as reducing and hydrostannylating agents. See ref. ⁶, ref.¹⁴, and the following references:

16a Shibata I. Kato H. Kanazawa N. Yasuda M. Baba A. Synlett  2004,  137 

16b Shibata I. Baba A. Curr. Org. Chem.  2002,  6:  665 ; and references therein

17 Silverstein RM. Bassler GC. Morrill TC. Spectrometric Identification of Organic Compounds   5th ed.:  Wiley; New York: 1991. 

18

The formation of Bu₂SnClH from Bu₂SnCl₂ and Bu₂SnH₂ is known to be reversible. The initiation of the present homolytic hydrostannylation may be caused by electron transfer from Bu₂SnH₂ to Bu₂SnCl₂, which forms the anion radical of Bu₂SnCl₂. See ref. [12b]

19a Fugami K. Ohnuma S. Kameyama M. Saotome T. Kosugi M. Synlett  1999,  63 

19b Fouquet E. Pereyre M. Rodriguez AL. J. Org. Chem.  1997,  62:  5242 

20a Martinez AG. Barcina JO. de Fresno Cerezo A. Subramanian LR. Synlett  1994,  1047 

20b Vedejs E. Haight AR. Moss WO. J. Am. Chem. Soc.  1992,  114:  6556 

21

General Procedure for the Subsequent Pd-Catalyzed Cross-Coupling:
PPh₃, Pd₂(dba)₃·CHCl₃, TBAF (1.0 M in THF, 1.5 mmol), and a haloarene (0.550 mmol) were added successively to the reaction mixture obtained by the hydrostannylation of 1a or 8c (0.500 mmol). After being stirred at 60 °C for a given time, the resultant mixture was cooled to r.t. and diluted with t-BuOMe (10 mL). After addition of DBU (0.5 mL), the mixture was stirred for 5-10 min, passed through a short silica gel column, and evaporated. Purification of the residual oil was performed by silica gel column chromatography.

22 Espinet P. Echavarren AM. Angew. Chem. Int. Ed.  2004,  43:  4704