A Convenient Mannich-Type One-Pot Synthesis of Pyrimido[6,1-b][1,3,5]thiadiazines

摘要

3-(Het)aryl-2-cyanoprop-2-enethioamides easily reacted with primary amines and excessive formaldehyde under mild conditions to afford pyrimido[6,1-6][1,3,5]thiadiazine derivatives in moderate yields.Furthermore,2-cyano-2-cyclohexylideneethanethioamide reacted in the similar Mannich-type manner to give spiro-conjugated pyrimido-1,3,5-thiadiazines.The structure of 3,7-dibenzyl-8-(fur-2-yl)-3,4,7,8-tetrahydro-2H,6H-pyrimido[6,1-b][1,3,5]thiadiazine-9-carbo-nitrile was determined by X-ray diffraction analysis.