Annulations of Enantioenriched Allenylsilanes with in Situ Generated Iminium Ions: Stereoselective Synthesis of Diverse Heterocycles
作者:Ryan A. Brawn、James S. Panek
DOI:10.1021/ol802618p
日期:2009.1.15
mediated annulations with in situ generated iminium ions derived from tert-butyl carbamate and methyl carbamate to selectively form functionalized 4,5-dihydropyrroles and 4,5-dihyrooxazines, respectively. The dihydropyrrole products were further elaborated in a stereocontrolled vinylsilane terminated cyclization with in situ generated oxoniumions, resulting in pyranopyrroles.
Preparation of (Ra)-Methyl 3-(dimethyl(phenyl)silyl)hexa-3,4-dienoate
作者:Brawn, Ryan A.、Panek, James S.
DOI:10.15227/orgsyn.089.0420
日期:——
Stereoselective Synthesis of Polysubstituted Tetrahydropyranones via Acid-Promoted Cyclization of β-Silyl-γ-ethylidene-γ-butyrolactones with Aldehydes and Ketones
β-Silyl-γ-ethylidene-γ-butyrolactone upon one-pot treatment with aldehydes and ketones in the presence of Lewis acids underwent a tandem Hosomi–Sakurai/Prins cyclization to give polysubstituted tetrahydropyranones stereoselectively. Various aldehydes and ketones can be used in this reaction to produce the corresponding tetrahydropyranones. The optical purity of the starting γ-butyrolactone was substantially