Unique Steric Effect of Geminal Bis(silane) To Control the High Exo-selectivity in Intermolecular Diels–Alder Reaction

Abstract

The unique steric effect of geminal bis(silane) [(R3Si)2CH] allows an exo-selective intermolecular Diels-Alder reaction of geminal bis(silyl) dienes with α,β-unsaturated carbonyl compounds. The approach shows good generality to form ortho-trans cyclohexenes in good yields with high exo-selectivity and high enantioselectivity in some asymmetric cases. The excellent exo-stereocontrol aptitude of (R3Si)2CH group is highlighted by comparing with R3SiCH2 and R3Si groups, which leads to endo-selectivity predominantly. The conformational analysis of dienes suggests that (R3Si)2CH group effectively shields both sides of the diene moiety, ensuring the desired exo-selectivity. Moreover, the geminal bis(silane) can be further functionalized to transform the resulting ortho-trans cycloadducts into useful synthons, which makes the approach hold great potential for organic synthesis.

Recent Progress in the Transition‐Metal‐Catalyzed Activation of Si−Si Bonds To Form C−Si Bonds

“…This species possesses unique sterica nd electronic effects, allowing as eries of useful transformations. [46] The synthesis of geminal bis(silanes) is challenging because of steric repulsion between the two silicon atoms. Towards such as ynthesis, Wang and coworkers have recently described am ethodf or the palladiumcatalyzed insertion of carbenes into the SiÀSi bond of disilanes (Scheme 31).…”

Cobalt-Catalyzed Asymmetric Synthesis of gem-Bis(silyl)alkanes by Double Hydrosilylation of Aliphatic Terminal Alkynes

“…[32][33][34] Compared with single-silyl compounds, bis(silyl) ones are understudied because of the lack of efficient synthetic protocols. [35][36][37][38] The development of efficient synthetic processes to access various bis(silyl) compounds is highly desirable for studying their basic properties and exploring their potential utilities.…”

Experimental and Computational Investigations of the Reactions between α,β‐Unsaturated Lactones and 1,3‐Dienes by Cooperative Lewis Acid/Brønsted Acid Catalysis

“…Currently, only few methods are established for the reaction of α,β‐unsaturated lactones with unsubstituted 1,3‐dienes, alkynes, and bis(SiEt 3 )‐substituted dienes towards bicyclic isochromenones, whereupon none leads to 6,8‐dihydroxyisochroman‐1‐ones. The reported methods describe a concerted Diels–Alder type reaction between α,β‐unsaturated δ‐lactones with different types of dienes.…”