Stereoselective Synthesis of 4‐Hydroxy‐1‐Silyl‐1‐Allenylboranes and Access to 2‐Silylethynyl‐1,3‐Diols - Réactivité organométallique et catalyse pour la synthèse
Article Dans Une Revue Asian Journal of Organic Chemistry Année : 2024

Stereoselective Synthesis of 4‐Hydroxy‐1‐Silyl‐1‐Allenylboranes and Access to 2‐Silylethynyl‐1,3‐Diols

Résumé

The highly stereoselective gem ‐silylboration of chiral 2‐substituted 1‐ethynylepoxides is reported herein. The reaction involves first the deprotonation of the epoxides in the acetylenic position followed by transmetallation with Et3SiBpin. The transient silylborane ate‐complexes generated undergo the stereoselective 1,2‐migration of the Et3Si‐group to the sp‐hybridized terminus carbon of the ethynyl‐moiety in a stereospecific anti‐addition. The moisture‐sensitive and thermally unstable 4‐hydroxy‐1‐triethylsilyl‐1‐allenyl(pinacolato)boranes thus obtained react with aldehydes through an SE2’‐mode of addition, affording highly functionalized 2‐triethysilylethynyl‐1,3‐diols with a good diastereoselectivity which is rationalized by a Yamamoto‐Houk type transition state model.

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Chimie organique
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Dates et versions

hal-04737222 , version 1 (15-10-2024)

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Ichrak El Haj Brahim, Islem Ishak Dridi, Raoudha Abderrahim, Fabrice Chemla, Franck Ferreira, et al.. Stereoselective Synthesis of 4‐Hydroxy‐1‐Silyl‐1‐Allenylboranes and Access to 2‐Silylethynyl‐1,3‐Diols. Asian Journal of Organic Chemistry, 2024, 13 (5), pp.e202400042. ⟨10.1002/ajoc.202400042⟩. ⟨hal-04737222⟩
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