R₃Al−R‘₃SiOTf:  Novel and Powerful Reagent System for Stereospecific Alkylation−Silylation Reactions of Epoxides

Abstract

[reaction: see text] A novel and powerful reagent system R(3)Al-R'(3)SiOTf for the one-pot alkylation-silylation reaction of epoxides was discovered, and the reactions of various epoxides with the new reagent system have been demonstrated to occur stereospecifically giving rise to the corresponding alkylation-silylation products in excellent yields.

Exploiting Hidden Symmetry in Natural Products: Total Syntheses of Amphidinolides C and F

“…Subsequent oxidation using DMP yielded tetra-TBS protected amphidinolide C. Gratifyingly, global deprotection using Et 3 N•3HF produced the natural product 1 , which was matched nicely with the observed spectra ( 1 H, 13 C NMR in C 6 D 6 ). 12b–c Additionally, the optical rotation data was in agreement with the literature value [Synthetic: [α] D 23 = −98.5° ( c = 0.21, CHCl 3 ); Natural: 12 [α] D 26 = −106° ( c = 1.0, CHCl 3 )]. This approach constitutes a 28-step synthesis (LLS) of amphidinolide C ( 1 ).…”

Regioselective and Divergent Opening of Vinyl Epoxides with Alkyne Nucleophiles

“…Consequently, the relative stereochemistry of the formed homoallylic alcohols is directly related to the cis-or trans-stereochemistry of the starting vinyl epoxides, thus giving ready access to cis-or trans-β,γ-disubstituted γ-butyrolactones, respectively. Alkynylalanes have previously been used for ring-opening of oxiranes [18][19][20] and the soft character of these reagents has enabled Michael additions to enones. [21] Somewhat surprisingly, these reagents had not previously been exploited in S N 2Ј opening of vinyl epoxides.…”

Three‐Membered Heterocycles. Structure and Reactivity

“…The methyl group is delivered via backside attack on the less substituted terminus of the epoxide, and the alkoxide so formed is silylated in situ [533]. An ethyl group can be appended in like fashion using triethylaluminium catalyzed by triphenylphosphine [534].…”