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Rh(II)-Catalyzed Reactions of Diazoesters with Organozinc Reagents.

ABSTRACT: Rh(II)-catalyzed reactions of diazoesters with organozinc reagents are described. Diorganozinc reagents participate in reactions with diazo compounds by two distinct, catalyst-dependent mechanisms. With bulky diisopropylethyl acetate ligands, the reaction mechanism is proposed to involve initial formation of a Rh-carbene and subsequent carbozincation to give a zinc enolate. With Rh2(OAc)4, it is proposed that initial formation of an azine precedes 1,2-addition by an organozinc reagent. This straightforward route to the hydrazone products provides a useful method for preparing chiral quaternary ?-aminoesters or pyrazoles via the Paul-Knorr condensation with 1,3-diketones. Crossover and deuterium labeling experiments provide evidence for the mechanisms proposed.

SUBMITTER: Panish R

PROVIDER: S-EPMC4552333 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature

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Rh(II)-Catalyzed Reactions of Diazoesters with Organozinc Reagents.

Panish Robert R Selvaraj Ramajeyam R Fox Joseph M JM

Organic letters 20150804 16

Rh(II)-catalyzed reactions of diazoesters with organozinc reagents are described. Diorganozinc reagents participate in reactions with diazo compounds by two distinct, catalyst-dependent mechanisms. With bulky diisopropylethyl acetate ligands, the reaction mechanism is proposed to involve initial formation of a Rh-carbene and subsequent carbozincation to give a zinc enolate. With Rh2(OAc)4, it is proposed that initial formation of an azine precedes 1,2-addition by an organozinc reagent. This stra ...[more]

PMID: 26241081

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