Nitrosocarbonyl compounds in synthesis
Diels-Alder adducts have been prepared by the action of the
reactive intermediate, 2,2,2-trichloroethyl nitrosoformate, on a
series of simple conjugated dienes, and the reductive de-acylation
and cleavage of these adducts have been investigated. The methods
developed in this study have been applied to a new preparation of
14f-aminocodeinone via the cycloadduct of 2,2,2-trichloroethyl
nitrosoformate with thebaine. Nitrosyl hydride, HNO, produced by
the periodate oxidation of hydroxyl amine, has been trapped by
N-benzyloxycarbonylnorthebaine and N-t-butoxycarbony1northebaine to
form the corresponding cycloadducts. These thermally labile compounds
have been characterised by formation of their N-acetyl derivatives.
The intramolecular ene reactions of C-nitrosocarbonyl compounds
and nitrosoformates have been studied. The cyclisation of 1-nitrosocarbonylhept-
4-ene, generated by the thermal cleavage of its adduct
with 9,10-dimethylanthracene, did not proceed cleanly. However, five
olefinic nitrosoformates, generated by the thermal cleavage of their
cyclopentadiene adducts, have been shown to undergo intramolecular ene
reactions to give cyclic hydroxamic acids. The nitrosofoznates of
3,3-dimethtiylallyl alcohol, 2-methylprop-2-en-l-ol, 4-methylpent-3-en-
1-01,3-methylcyclohex-3-en-1-ol, and 4-methylcyclohex-3-en-1-ol,
cyclised to give 5,6,6,7, and 6-membered ring compounds respectively.
In each case only one mode of cyclisation was observed.