Homologating agent

Stowell, J. C. Three-carbon homologating agents. Chem. Rev. 1984, 84, 409—435. 

The formation of carbon-carbon bonds by means of three carbon homologating agents (d synthons) can provide a useful and desirable methodology for the preparation of inter alia, a,/5- and )5,7-unsaturated aldehydes. 

Silylated glutaconaldehyde (36) has been used as a five carbon homologating agent for the synthesis of pellitorine (1) and sarmentine (3) by reaction with w-pentylmagnesium bromide followed by oxidation to the corresponding acid and final amidation [58] (Scheme 14). 

A new synthesis of three sex pheromones, (171), (172) and (173), of the Winter moth Operophtera brumata involves the use of the ylide (174) which acts as a homologating agent and allows further Wittig reactions of the products after acetal deprotection.Standard methods of phosphonate-based olefination have been applied to the synthesis of new retinals, e.g. (175) and (176), with modified methyl substitution patterns. ... 

The anion derived from protected 2-hydroxy-5,6-dihydro-1,4-dithiin is efficiently attacked by electrophiles to give the 2,3-disubstituted dithiin. Both deprotection and desulfurisation are readily accomplished in the latter case, the dithiin functions as a 3-carbon homologating agent <97JOC9369>. 

Sandri, J., and J. Viala, Direct Preparation of (Z,Z) 1,4-Dienic Units with a New C6 Homologating Agent Synthesis of a-Linolenic Acid, Synthesis, 271-275 (1995). 

Preparation by Nucleophilic Addition.- The monoanion of 1, 4-dioxene has been developed as a two-carbon homologating agent for converting carbonyl compounds into B-keto-alcohols via an addition-... 

Two improved procedures for the preparation of borinic and boronic esters from "ate" complexes have been developed and a practical synthesis of dichloromethyl and 1,1-dichloroethyl boronic esters reported. The effectiveness of representative homologating agents for trialkyIboranes, borinic and boronic esters have been explored and LICHCI2, LiCHClSlMe3 and LiCH(OMe)SPh shown to work well with all three substrates. Other reagents are effective with trialkylboranes but not with boronic esters. Available procedures for homologation of boronic esters have been critically examined and a more convenient route reported. ... 

DIHYDRO-l,4-DITHIIN-2-YL)METHANOL NOT SIMPLY A HOMOLOGATING AGENT... 

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