Some Ph-ring-substituted phenacylthioimidazolines are very potent antagonists of reserpine-induced hypothermia in mice. The proportion of open chain to cyclic carbinolamine tautomer depends on the type of substituent and possibly affects the activity. [1][2][3][4][5][6] thiazoles obtained by cyclodehydration are also active.

The syntheses and structure--activity relationships of a number of 4-hydroxy-3-nitrocoumarins, which are both antagonists of a slow reacting substance of anaphylaxis and potent inhibitors of antigen-induced histamine release in the rat, are described. Most active among these are 7-[3-(4-acetyl-3-hydroxy-2-n-propylphenoxy(-2-hydroxypropoxy] derivatives having hydrogen or lower alkyl substituents at the C-8 position of the coumarin ring, 168, 171, 173, and 174.

c 0.85); lit.1' mp 103°, [a]u (THF) -20 ± 1°.

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