Frontiers in Natural Product Chemistry

Volume: 1

Indexed in: EBSCO.

“Frontiers in Natural Product Chemistry” is an Ebook series devoted to publishing the latest and most important advances in natural product chemistry. The Ebook series covers all aspects of ...
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Rhodium-Catalyzed Asymmetric 1,4-Addition of Organometallic Reagents

Pp. 3-17 (15)

Tamio Hayashi

Abstract

Asymmetric 1,4-arylation and -alkenylation was achieved by use of organoboronic acids or their derivatives in the presence of a rhodium catalyst coordinated with binap or its related ligands. The scope of this asymmetric addition is very broad, α,β-unsaturated ketones, esters, amides, 1- alkenylphosphonates, and 1-nitroalkenes being efficiently converted into the corresponding 1,4-addition products with over 95% enantioselectivity. The catalytic cycle of the reaction in water is proposed to involve three intermediates (aryl- or alkenyl-rhodium, (oxa-π-allyl)rhodium, and hydroxorhodium) by NMR studies on the rhodium intermediates. The asymmetric addition of B-aryl-9BBN and ArTi(OPr-i)3 in aprotic solvents proceeded with high enantioselectivity under mild conditions to give the corresponding metal enolates as the 1,4-addition products.

Keywords:

asymmetric reduction, oxidation, enantioselectivity, chiral transition, unsaturated ketones, dioxane, catalytic activity, cyclopentenone, hydrolysis, fluorobenzene

Affiliation:

Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan.