Abstract
Ketene S,S-acetals 1a, b or ketene N,S-acetals 2a, b reacts in situ with a variety of ylidenemalononitriles to afford the desired spiro [1,3]dithiin heterocycles 3a, b–11a, b or spiro[1,3]thiazine heterocycles 12a, b–20a, b. Treatment of 2-(1-acetyl-2-oxopropylidene)spiro[1,3]thiazine derivatives 13b, 17d, and 18d with malononitrile afforded the corresponding dispiro heterocycles 21, 22, and 23.
The author wishes to thank Dr. Jerzy Suwinski and Mr. Mounir Abbas, Institute of Organic Chemistry and Technology, Silesian Technical University, 44-100 Gliwice, Poland, for the empirical calculation.
Notes
a Uncorrected.
b Satisfactory microanalysis obtained C; +0.35, H; +0.4, N; +0.2.
c Measured on a Nicolet 710 FT-IR spectrometer.
d Measured by a Varian EM 360L spectrometer at 60 MHZ using TMS as internal standard and DMSO d6 as a solvent.