The stereoselectivity of the alkylation of the dianion of ethyl 2‐hydroxy‐6‐methylcyclohexanecarboxylates: Control of stereochemistry at three adjacent stereogenic centers

Abstract

Yeast reduction of rac -ethyl 2-methyl-6-oxocyclohexanecarboxylate (rac -1) yielded selectively (+)-ethyl 2-hydroxy-6-methylcyclohexane carboxylate (+)-2 (Scheme 1 ) which has been alkylated with 5-iodo-2-methylbut-2-ene by the dianion method to furnish the 4-methylbut-3-enyl derivat 3 (Scheme 3). NaBH4 reduction of (+)-l led to three hydroxy-carboxylates (-)-2, (+)-5, and (-)-6 (Scheme 4). Allylation of the dianion of (+)-5 afforded (+)-7.Introduction. -

An Alkyne Hydrosilylation-Oxidation Strategy for the Selective Installation of Oxygen Functionality

“…As aldol adducts are prone to further reactions such as eliminations, further substitution at the R-carbon becomes difficult. 20 Therefore, an important feature of this approach is the ability to introduce additional complexity at the R-carbon. For example, epoxidation occurs with complete diastereoselectivity with m-CPBA to provide hydroxy epoxide 15.…”

Regioselective Hydrosilylation of Propargylic Alcohols: An Aldol Surrogate

“…Despite the tremendous successes, deficiencies exist. As aldol adducts are prone to further reactions such as elimination, further substitution at the α‐carbon becomes difficult 1. Asymmetric additions of methyl alkyl ketones have been very limited 2.…”

Regioselective Hydrosilylation of Propargylic Alcohols: An Aldol Surrogate

“…As aldol adducts are prone to further reactions such as elimination, further substitution at the a-carbon becomes difficult. [1] Asymmetric additions of methyl alkyl ketones have been very limited. [2] Propargylic alcohols can become surrogates for aldols provided that a chemo-and regioselective introduction of a carbonyl group at the alkyne carbon b to the alcohol can be performed.…”