Benzyliden-verbindungen der pentonsäuren und pentonsäure-lactone

Abstract

Di- O-benzylidene derivatives of pentonic acids may be readily prepared by oxidation of the di- O-benzylidene- aldehydo-pentoses with chromium trioxide in N,N-dimethylformamide or by saponification of the corresponding methyl esters. Treatment of ammonium D-xylonate with benzaldehyde and hydrochloric acid gives the di- O-benzylidene- D-xylonic acid, whereas the D-ribonate and D-lyxonate salts give the 3,5- O-benzylidene-pentono-1,4-lactones. With benzaldehyde and zinc chloride, the methyl pentonates variously give the di- and mono- O-benzylidene derivatives and the mono- O-benzylidenepentonolactones. The structures of the di- O-benzylidene derivatives obey the rules of Hann and Hudson. The O-benzylidene-pentonolactones give the corresponding amides and hydrazides on treatment with ammonia and hydrazine hydrate, respectively; reduction with lithium aluminium hydride gives the O-benzylidenepentitols.