Styrene oxide optically pure

Optically pure (S)-benzyl methyl sulfoxide 139 can be converted to the corresponding a-lithio-derivative, which upon reaction with acetone gave a diastereomeric mixture (15 1) of the /S-hydroxysulfoxide 140. This addition reaction gave preferentially the product in which the configuration of the original carbanion is maintained. By this reaction, an optically active epoxy compound 142 was prepared from the cyclohexanone adduct 141181. Johnson and Schroeck188,189 succeeded in obtaining optically active styrene oxide by recrystallization of the condensation product of (+ )-(S)-n-butyl methyl sulfoxide 143 with benzaldehyde. 

The complex [PtCl2(DIOP)] in the presence of SnCl2 has been used as catalyst for the asymmetric hydroformylation of various alkenes. With a series of butene and styrene derivatives very low optical yields were obtained. The best results were achieved with 2,3-dimethyl-l-butene which gave 15% optically pure 3,4-dimethylpentanal, and with a-ethylstyrene which gave 15% optically pure 3-phenylpentanoic acid after oxidation of the aldehyde.373... 

Both diastereomeric pairs of catalyst 30 and 31 were prepared in two steps, starting with a ring opening of optically pure styrene oxide with chiral amines, followed by alkylation. Interestingly, the alkylation of glycinate derivative 20 using 30a showed a... 

Hydroformylation of styrene and its analogues has attracted particular attention, since this provides a general method for the preparations of optically pure arylpropionic acids. Apart from Naproxen , the drug ibuprofen is another ar-ylpropionic acid-based nonsteroidal anti-inflammatory agent. As shown by 9.9, ibuprofen may in principle be synthesized by enantioselective hydroformylation reactions followed by oxidation of the aldehydic functionality. 

The importance to use optically pure isomers as pharmaceuticals, food additives, agrochemicals, (etc) is becoming more and more evident. The classical resolution still accounts for a large part of chiral production, however the asymmetric synthesis and the use of chiral separation system one becoming increasingly popular. The enantioseletive hydrolytic resolution of racemic epoxides was performed in the ZSM-5/MCM-41 membrane system containing chiral salen complexes. The chiral salen complexes immobilized on the membrane showed a very high enantioselectivity in the hydrolysis of epichlorohydrine, epoxybutane, styrene oxide and 1,2-epoxyhexane. 

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