Azo anions in systhesis. pt 1. t-butylhydrazones as acyl-anion equivalents
作者:Jack E. Baldwin、Robert M. Adlington、Jeffrey C. Bottaro、Jayant N. Kolhe、Matthew W.D. Perry、Ashok U. Jain
DOI:10.1016/s0040-4020(01)87647-x
日期:1986.1
tautomerisation and hydrolysis gave α-hydroxy ketones, ketones, and γ-keto esters in good yield, thereby providing a convenient new acyl-anionequivalent. Reaction of these lithium salts with aldehydes and ketones, followed by elimination provided a new route to azo alkenes.
The present invention relates to a new process for the generation of pyrazines consisting in the bioconversion of hydroxyketones with 1,2-diaminopropane. New tetrahydropyrazine derivatives as well as new dihydropyrazine derivatives with high flavour and low threshold properties are disclosed. Such pyrazines compounds exhibiting roasted and earthy aroma profiles may be used in the food and bevererage industry, especially chocolate, confectionery and coffee.
The oxidation of α ketone imine carbanions gives primary α ketols from methylketones, and secondary α ketols from symmetric ketones. Secondary α ketols may also be isolated by oxidation of carbanions of methylketone oximes. By using manganese dioxide, these secondary ketols may be oxidized to α diketones.
Osmium tetroxyde-catalyzed dihydroxylation of alleniccompounds in the presence of N-Methylmorpholine Oxide leads to α-ketols. Regioselectivity of this oxidation procedure with allenic α-amino acidprecursors is greatly influenced by the nature and the remoteness of the protected aminoacid group.