Heterocyclic organometallic reagents

Where a heterocyclic organometallic reagent is required, Grignard and zinc derivatives are often satisfactory complications sometimes attend the use of lithio derivatives. The use of boronic acids has become very popular on account of their clean reactions, general stability to air and water, and their compatibility with practically any functional group furan, thiophene, indole and pyridine boronic acids have all been used. " ... 

Preparation of Heterocyclic Enamines by Means of Organometallic Reagents... 

Reactivity and selectivity of organometallic reagents addition to C=N bond with participation and formation of heterocycles 98CRV1407. 

The reaction of 3-benzoxepin with methyllithium results in the addition of two equivalents of the organometallic reagent and cleavage of the heterocycle. After hydrolysis l-[2-(Z)-prop-l-enyl)phenyl]propan-2-ol can be isolated, but no experimental data is available.216 Occasionally, a small amount of the tran.v-isomcr is obtained (less than 10% of the product).12... 

Organometallic reagents are better known for their involvement in the alkylations at ring nitrogen atoms in many heterocycles. However, under proper circumstances, they can promote addition to carbonyl groups. Such is the case when 68 is allowed to react with an excess of Me2BuMgLi at 0°C. The secondary alcohol 69 is obtained in fair yield (Equation 28) <20040L1991>. 

A route to pyrroles illustrated by the preparation of 292 involves initial treatment of the nitroketene-5, 5 -acetal 293 with an organometallic reagent, followed by conversion of the resulting alkene 294 to the enamine 295, and final annulation to the target heterocycle (Scheme 34) <1998T12973>. A related approach featuring constmction of /3-hydroxyenamines from 1,3-dicarbonyl compounds and /3-amino alcohols, and subsequent palladium-catalyzed cyclization to pyrroles, has been reported <1996TL9203>. 

Other useful organometallic reagents for the preparation of tertiary stibines or related heterocyclic compounds are compounds of lithium, aluminum, tin, copper, zirconium, and other metals. " In most cases, these metal compounds are reacted with antimony chlorides or bromides. Good yields of tertiary stibines were, however, also obtained by the interaction (equation 3) of triaUcylaluminium reagents and tris(dimethylamino)stibine. ... 

The C4-chiral thiazolidine-2-thiones and oxazolidine-2-thiones developed by us proved to be efficient for chiral induction. They should be applicable to practical syntheses of drugs. Novel chiral designs using these functional and chiral heterocycles seem likely in the future, especially when used in combination with organometallic reagents and/or molecular symmetry. Creative investigations employing such chiral heterocycles and related compounds will be extensively pursued. 

Addition of an aryl organometallic reagent to an alkyne followed by thermolysis has been used to form heterocyclic analogs of indene ... 

Enantioselective addition of allylic organometallic reagents to aldehydes and ketones using heterocycles as ligands 03CRV2763. 

Hetaryl sulfoxides, reactions with organometallic reagents 86PS(27)13. Heterocycles, functional group transformations using Pd compounds ... 

Ketones can be prepared starting from esters via the intermediate 2-acylbenzothiazoles (511) which are easily obtained by condensation with 2-lithiobenzothiazole (230). The reaction of these compounds with an organometallic reagent and subsequent quaternization of the heterocyclic ring affords the A -methylbenzothiazolium salts (512) which upon treatment with a base yield the corresponding ketones (Scheme 120) <91BCJ3256>. 

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