Alkyl formhydroximates have been synthesized by reacting alkyl orthoes
ters with hydrogen sulfide followed by treatment of the alkyl thioform
ate formed with hydroxylamine. Chlorination of alkyl formhydroximates
with N-chlorosuccinimide gives alkyl chloroformhydroximates and dehydr
ochlorination with base generated alkoxynitrile oxides (alkyl cyanate
N-oxides), which efficiently undergo cycloaddition to olefins or acety
lenes to give 3-alkoxyisoxazolines or 3-alkoxyisoxazoles, respectively
. These compounds are masked beta-hydroxy- and beta-keto-esters. Reduc
tive cleavage of the ring was performed by hydrogenation over Raney-Ni
or with Ti3+ salts. The reaction thus constitutes a novel hydroxycarb
oxylation. DL-N-Boc-gamma-amino-beta-hydroxybutyrates (Gabob), mevalon
ic acid, citromalic acid, malic acid derivatives and N-methyl-N-hydrox
ythioformamide (thioformin) have been synthesized. N,N-Dimethyl-N'-hyd
roxychloroformamidine (N,N-dimethylaminochloroform oxime) was not form
ed by chlorination of N,N-dimethyl-N'-hydroxyformamidine. The nitrile
oxide cycloaddition to cycloheptatriene was investigated. The [6 + 4]
cycloaddition mode was not observed but three isomeric [4 + 2] cycload
dition products were isolated and structurally determined.