Allenes. ethyl isocyanate

ALLENES a-Bromovinyltrimethyl-silane. Lithium acetylide. Lithium aluminum hydride. l-(l-Naphthyl)-ethyl isocyanate. 

Simple chiral allenes have been prepared by the reaction of propargylic carbamates with lithium dialkylcuprates. The diastereomeric carbamates, derived from racemic propargylic alcohols and (/ )-1-(l-naphthyl)ethyl isocyanate, are readily separated by h.p.l.c. they are then treated with lithium dialkycuprates at -78 °C, producing the allenes with enantiomeric excess up to 80% in yields of around 70% (Scheme 2). The method is claimed to be an improvement on earlier methods in that it is much simpler and gives better optical yields. 

P. Walden34 has studied soln. of iodine in acetaldehyde, hydrazine hydrate, and acetonitrile J. H. Mathews, soln. of iodine in pyridine, ethyl, allyl, and plienyl isothiocyanic esters, and phenyl isocyanate while H. A. Allen has studied soln. of bromine and iodine in various oils. 

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See also in sourсe #XX -- [ ]

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