Robert Panish1, Ramajeyam Selvaraj1, Joseph M Fox1. 1. Brown Laboratories, Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States.
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 α-aminoesters or pyrazoles via the Paul-Knorr condensation with 1,3-diketones. Crossover and deuterium labeling experiments provide evidence for the mechanisms proposed.
Rh(II)-catalyzed reactions of n class="Chemical">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 α-aminoesters or pyrazoles via the Paul-Knorr condensation with 1,3-diketones. Crossover and deuterium labeling experiments provide evidence for the mechanisms proposed.
Authors: Tom A Targel; Jayprakash N Kumar; O Svetlana Shneider; Sukanta Bar; Natalia Fridman; Shimon Maximenko; Alex M Szpilman Journal: Org Biomol Chem Date: 2015-03-07 Impact factor: 3.876
Authors: Robert Panish; Srinivasa R Chintala; David T Boruta; Yinzhi Fang; Michael T Taylor; Joseph M Fox Journal: J Am Chem Soc Date: 2013-06-12 Impact factor: 15.419