Abstract
Treatment of iodo carbonates with LiHMDS at low temperature readily affords cyclic enol carbonates with either five- or six-membered rings. Reaction with potassium tert -butoxide results in the in situ formation of an enolate which after transmetallation participates in aldol or Mannich reactions. Alternatively, the potassium enolates can be trapped with silylating or triflating agents. The regio- and stereoselective generation of silyl enol ethers with up to four substituents can be achieved.
Key words
enols - aldol reactions - tandem reactions - stereoselectivity - regioselectivity
References
1a Cardillo G.
Orena M.
Porzi G.
Sandri S.
J. Chem. Soc., Chem. Commun.
1981,
465
1b Bongini A.
Cardillo G.
Orena M.
Porzi G.
Sandri S.
J. Org. Chem.
1982,
47:
4626
2a Bartlett PA.
Meadows JD.
Brown EG.
Morimoto A.
Jernstedt KK.
J. Org. Chem.
1982,
47:
4013
2b Smith AB.
Duan JJ.-W.
J. Org. Chem.
1993,
58:
3703
3a Sasaki Y.
Tetrahedron Lett.
1986,
27:
1573
3b Inoue Y.
Ishikawa J.
Taniguchi M.
Hashimoto H.
Bull. Chem. Soc. Jpn.
1987,
60:
1204
3c Kwon S.-C.
Cho C.-S.
Shim S.-C.
Kim T.-J.
Bull. Korean Chem. Soc.
1999,
20:
103
3d Fournier J.
Bruneau C.
Dixneuf PH.
Tetrahedron Lett.
1989,
30:
3981
3e Costa M.
Chiusoli GP.
Rizzardi M.
Chem. Commun.
1996,
1699
3f Iritani K.
Yanagihara N.
Utimoto K.
J. Org. Chem.
1986,
51:
5499
3g Inoue Y.
Itoh Y.
Yen I.-F.
Imaizumi S.
J. Mol. Catal.
1990,
60:
L1
4a Joumier J.-M.
Grainger R.
Bruneau C.
Dixneuf PH.
Synlett
1993,
423
4b Laas H.
Nissen A.
Nurrenbbach A.
Synthesis
1981,
958
5a Joumier M.-M.
Fournier J.
Bruneau C.
Dixneuf PH.
J. Chem. Soc., Perkin Trans. 1
1991,
3271
5b Inoue Y.
Ohuchi K.
Imaizumi S.
Tetrahedron Lett.
1988,
29:
5941
5c Inoue Y.
Matsushita K.
Yen I.-F.
Imaizui S.
Chem. Lett.
1991,
1377
5d Ohe K.
Matsuda H.
Ishihara T.
Ogoshi S.
Chatani N.
Murai S.
J. Org. Chem.
1993,
58:
1173
5e Ohe K.
Matsuda H.
Morimoto T.
Ogoshi S.
Chatani N.
Murai S.
J. Am. Chem. Soc.
1994,
116:
4125
6 Ogoshi S.
Morimoto T.
Nishio K.-I.
Ohe K.
Murai S.
J. Org. Chem.
1993,
58:
9
7 Le Gendre P.
Braun T.
Bruneau C.
Dixneuf PH.
J. Org. Chem.
1996,
61:
8453
8 Marshall JA.
Yanik MM.
J. Org. Chem.
1999,
64:
3798
9 Raimundo BC.
Heathcock CH.
Org. Lett.
2000,
2:
27
10 Mahoney W.
Brestensky D.
Stryker J.
J. Am. Chem. Soc.
1988,
110:
291
11 Additional details for the preparation of substrates including isolation and characterization data are available upon request.
12 A procedure employing BuLi was also used extensively.
13 Due to inseparable mixtures and low diastereomeric ratios, full results are not reported at this time although representative procedures are provided.
14 McMurry JG.
Scott WJ.
Tetrahedron Lett.
1983,
24:
979
15 Purified by flash chromatography utilizing an eluent that contained 0.5% Et3 N. Trimethylsilyl and triethylsilyl triflates gave products of low stability.
16 tert -butyl carbonate moiety have previously been prepared. Nor have the parent ketone compounds ever been used directly in an aldol or Michael reaction. This is perhaps a reflection of their base sensitivity
17 Touleec P.
Martin AC.
Gio-Batta M.
Bruneau C.
Dixneuf PH.
Tetrahedron Lett.
2000,
41:
5527
18 Iritani K.
Yanagihara N.
Utimoto K.
J. Org. Chem.
1986,
51:
5501
19a Haner R.
Laube T.
Seebach D.
J. Am. Chem. Soc.
1985,
107:
5396
19b Baigrie LM.
Lenoir D.
Seikaly HR.
Tidwell TT.
J. Org. Chem.
1985,
50:
2105
19c Baigrie LM.
Seikaly HR.
Tidwell TT.
J. Am. Chem. Soc.
1985,
107:
5391
19d O’Neill P.
Hegarty AF.
J. Org. Chem.
1987,
52:
2113
20 Gazzard LJ.
Motherwell WB.
Sandham DA.
J. Chem. Soc., Perkin Trans. 1
1999,
8:
979
21 Fehr C.
Galindo J.
J. Org. Chem.
1988,
53:
1830
22 Cardillo G.
Orena M.
Porzi G.
Sandri S.
Tomasini C.
J. Org. Chem.
1984,
49:
701
