2-silyloxy-1,2-oxazines, a new type of acetals of conjugated nitroso alkenes.
3-alkyl-substituted 1,2-oxazine N-oxides 2 can be selectively transformed into 2-silyloxy-1,2-oxazines 1 upon treatment with silylating reagents. In the solid state derivatives 1 adopt a chair conformation with the pyramidal nitrogen atom, whereas in solution they exist as an equilibrating mixture of two conformers (DeltaG++ 55-60 kJ/mol). A preliminary study of the reactivity of nitrosals 1 has shown that they react with O- and N-stabilized carbocations to yield 1,2-oxazine N-oxides with a functionalized alkyl substituent at the 3-position. Moreover, compounds 1 can rearrange into silyloxy-1,2-oxazines 5 and react with morpholine to produce 3-morpholinoalkyl-1,2-oxazines 7 existing in a tautameric equilibrium with open-chain oximes 6.
Tishkov
Alexander A
AA
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Leninsky Prosp. 47, Moscow, Russian Federation.
Lesiv
Alexey V
AV
Khomutova
Yulya A
YA
Strelenko
Yury A
YA
Nesterov
Ivan D
ID
Antipin
Michael Yu
MY
Ioffe
Sema L
SL
Denmark
Scott E
SE