Dataset Information

Practical and Broadly Applicable Catalytic Enantioselective Additions of Allyl-B(pin) Compounds to Ketones and ?-Ketoesters.

ABSTRACT: A set of broadly applicable methods for efficient catalytic additions of easy-to-handle allyl-B(pin) (pin=pinacolato) compounds to ketones and acyclic ?-ketoesters was developed. Accordingly, a large array of tertiary alcohols can be obtained in 60 to >98?% yield and up to 99:1 enantiomeric ratio. At the heart of this development is rational alteration of the structures of the small-molecule aminophenol-based catalysts. Notably, with ketones, increasing the size of a catalyst moiety (tBu to SiPh3 ) results in much higher enantioselectivity. With ?-ketoesters, on the other hand, not only does the opposite hold true, since Me substitution leads to substantially higher enantioselectivity, but the sense of the selectivity is reversed as well.

SUBMITTER: Robbins DW

PROVIDER: S-EPMC4978177 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Practical and Broadly Applicable Catalytic Enantioselective Additions of Allyl-B(pin) Compounds to Ketones and α-Ketoesters.

Robbins Daniel W DW Lee KyungA K Silverio Daniel L DL Volkov Alexey A Torker Sebastian S Hoveyda Amir H AH

Angewandte Chemie (International ed. in English) 20160607 33

A set of broadly applicable methods for efficient catalytic additions of easy-to-handle allyl-B(pin) (pin=pinacolato) compounds to ketones and acyclic α-ketoesters was developed. Accordingly, a large array of tertiary alcohols can be obtained in 60 to >98 % yield and up to 99:1 enantiomeric ratio. At the heart of this development is rational alteration of the structures of the small-molecule aminophenol-based catalysts. Notably, with ketones, increasing the size of a catalyst moiety (tBu to SiPh ...[more]

PMID: 27273249

Similar Datasets

Project description:Conjugate (or 1,4-) additions of carbanionic species to α,β-unsaturated carbonyl compounds are vital to research in organic and medicinal chemistry, and there are several chiral catalysts that facilitate the catalytic enantioselective additions of nucleophiles to enoates. Nonetheless, catalytic enantioselective 1,6-conjugate additions are uncommon, and ones that incorporate readily functionalizable moieties, such as propargyl or allyl groups, into acyclic α,β,γ,δ-doubly unsaturated acceptors are unknown. Chemical transformations that could generate a new bond at the C6 position of a dienoate are particularly desirable because the resulting products could then be subjected to further modifications. However, such reactions, especially when dienoates contain two equally substituted olefins, are scarce and are confined to reactions promoted by a phosphine-copper catalyst (with an alkyl Grignard reagent, dialkylzinc or trialkylaluminium compounds), a diene-iridium catalyst (with arylboroxines), or a bisphosphine-cobalt catalyst (with monosilyl-acetylenes). 1,6-Conjugate additions are otherwise limited to substrates where there is full substitution at the C4 position. It is unclear why certain catalysts favour bond formation at C6, and-although there are a small number of catalytic enantioselective conjugate allyl additions-related 1,6-additions and processes involving a propargyl unit are non-existent. Here we show that an easily accessible organocopper catalyst can promote 1,6-conjugate additions of propargyl and 2-boryl-substituted allyl groups to acyclic dienoates with high selectivity. A commercially available allenyl-boron compound or a monosubstituted allene may be used. Products can be obtained in up to 83 per cent yield, >98:2 diastereomeric ratio (for allyl additions) and 99:1 enantiomeric ratio. We elucidate the mechanistic details, including the origins of high site selectivity (1,6- versus 1,4-) and enantioselectivity as a function of the catalyst structure and reaction type, by means of density functional theory calculations. The utility of the approach is highlighted by an application towards enantioselective synthesis of the anti-HIV agent (-)-equisetin.

Dataset Information

Practical and Broadly Applicable Catalytic Enantioselective Additions of Allyl-B(pin) Compounds to Ketones and ?-Ketoesters.

Publications

Practical and Broadly Applicable Catalytic Enantioselective Additions of Allyl-B(pin) Compounds to Ketones and α-Ketoesters.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets