Accession Number : ADA290594
Title : Super Hydrides.
Descriptive Note : Final rept. 31 Jul 91-31 Jul 94,
Corporate Author : PURDUE UNIV LAFAYETTE IN
Personal Author(s) : Brown, Herbert C.
PDF Url : ADA290594
Report Date : 31 OCT 1994
Pagination or Media Count : 28
Abstract : Beta-Chlorodiisopinocampheylborane (DIP-Chloride) introduced by us several years ago is an excellent reagent for the asymmetric reduction of aralkyl and alpha-hindered ketones. We have now shown that this reagent is extremely efficient for the reduction of aryl and alkyl perfluoroalkyl ketones, including alpha-perfluoroalkyl alpha-acetylenic ketones, generally providing (greater than or equal) 90% ee for the product alcohols. A systematic study of the electronic and steric influence in the reduction of fluoroalkyl ketones with DIP-Chloride and Beta-isopiocampheyl-9-borabicyclo onane (Alpine-Borane), and a comparison of the reduction of fluoroalkyl ketones with that of the corresponding chloroalkyl ketones have been made. The compatibility of DIP-Chloride with different functional groups substituted in the phenyl ring of acetophenone has been studied. The results show that most groups are compatible with the reagent. However, ortho-hydroxyl and carboxyl substitutions result in the opposite configuration for the product alcohol, probably due to a chelation followed by intramolecular reduction. DIP-Chloride reacts with o,o-disubstituted acetophenones with reduced rate and decreased ee for the product alcohols. The utility of DIP-Chloride in the syntheses of optically pure pharmaceuticals, such as an analog of BMS-181100 and eprozinol has been demonstrated. Studies to prepare new and improved asymmetric reducing reagents led to diiso-2-Beta-chloroethylapopinocampheylborane (Cleap2BC1). This reagent reduces representative ketones of 8 of the 10 classes to the corresponding sec-alcohols in excellent ee. (jg)
Descriptors : *HYDRIDES, *KETONES, *BORANES, CHELATION, RATES, REDUCTION, ASYMMETRY, FLUORINE, CHLORIDES, ORGANIC COMPOUNDS, ARYL RADICALS, RINGS, PHENYL RADICALS, MOLECULAR PROPERTIES, PHENOLS, INORGANIC COMPOUNDS, ALKYL RADICALS, ALCOHOLS, ACETOPHENONES.
Subject Categories : Inorganic Chemistry
Distribution Statement : APPROVED FOR PUBLIC RELEASE