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Libraries of Bisdiazaphospholanes and Optimization of Rhodium-Catalyzed Enantioselective Hydroformylation

Libraries of Bisdiazaphospholanes and Optimization of Rhodium-Catalyzed Enantioselective Hydroformylation

Tyler T Adint, Gene W Wong, Clark R Landis

J Org Chem. 2013 May 3;78(9):4231-8.

PMID: 23581247

Abstract:

Twelve chiral bis-3,4-diazaphospholane ligands and six alkene substrates (styrene, vinyl acetate, allyloxy-tert-butyldimethylsilane, (E)-1-phenyl-1,3-butadiene, 2,3-dihydrofuran, and 2,5-dihydrofuran) probe the influence of steric bulk on the activity and selectivity of asymmetric hydroformylation (AHF) catalysts. Reaction of an enantiopure bisdiazaphospholane tetraacyl fluoride with primary or secondary amines yields a small library of tetracarboxamides. For all six substrates, manipulation of reaction conditions and bisdiazaphospholane ligands enables state-of-the-art performance (90% or higher ee, good regioselectivity, and high turnover rates). For the nondihydrofuran substrates, the previously reported ligand, (S,S)-2, is generally most effective. However, optimal regio- and enantioselective hydroformylation of 2,3-dihydrofuran (up to 3.8:1 α-isomer/β-isomer ratio and 90% ee for the α-isomer) and 2,5-dihydrofuran (up to <1:30 α-isomer/β-isomer ratio and 95% ee for the β-isomer) arises from bisdiazaphospholanes containing tertiary carboxamides. Hydroformylation of either 2,3- or 2,5-dihydrofuran yields some of the β-formyl product. However, the absolute sense of stereochemistry is inverted. A stereoelectronic map rationalizes the opposing enantiopreferences.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP29681570	tert-Butyldimethylsilane		29681-57-0	Price

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