On the mechanism and diastereoselectivity of 2,3-dihydrobenzofuran formation from sulfinylbenzoquinones and 2-trimethylsilyloxyfuran
摘要:
A mechanistic study of the reactions between 2-trimethyisilyloxyfuran 1 and (SS)-2-(arylsulfinyl)- 1,4-benzoquinones 2a and 2b, giving rise to the diastereoselective formation of [3aS,8bS,SS]-3a,8b-dihydro-7-hydroxy-8-(arylsulfinyl)furo[3,2-b]benzofuran-2(3H)-ones 3a and 3b, is reported. The detection and H-1 NMR characterization of several precursors of 3a and 3b accounts for a Michael-type initial reaction which dictates the final diastereoselection of the process. A significant improvement of the stereoselectivity (up to 96% de) in the formation of the tert-butylsulfinyl substituted derivative 3c was achieved by using 2-(tert-butylsulfinyl)- 1,4-benzoquinone 2c as the starting quinone. (C) 1999 Elsevier Science Ltd. All rights reserved.
On the mechanism and diastereoselectivity of 2,3-dihydrobenzofuran formation from sulfinylbenzoquinones and 2-trimethylsilyloxyfuran
摘要:
A mechanistic study of the reactions between 2-trimethyisilyloxyfuran 1 and (SS)-2-(arylsulfinyl)- 1,4-benzoquinones 2a and 2b, giving rise to the diastereoselective formation of [3aS,8bS,SS]-3a,8b-dihydro-7-hydroxy-8-(arylsulfinyl)furo[3,2-b]benzofuran-2(3H)-ones 3a and 3b, is reported. The detection and H-1 NMR characterization of several precursors of 3a and 3b accounts for a Michael-type initial reaction which dictates the final diastereoselection of the process. A significant improvement of the stereoselectivity (up to 96% de) in the formation of the tert-butylsulfinyl substituted derivative 3c was achieved by using 2-(tert-butylsulfinyl)- 1,4-benzoquinone 2c as the starting quinone. (C) 1999 Elsevier Science Ltd. All rights reserved.