Synthesis of new α-spiroheteryl-fused butanolides

Abstract

Halogen-substituted butanolides [1-3] provide a good raw-material base for the synthesis of various types of compounds that are of certain biological interest [4][5][6][7]. While continuing our investigations in the series of 4-alkoxymethylbutanolides [3], we realized the bromination of 4-alkoxymethyl-2-ethoxycarbonylbutanolides 1a,b with bromine in dry carbon tetrachloride at room temperature with the formation of high yields (88-89%) of the corresponding 2-bromo derivatives 2a,b. O ROCH 2 COOEt O Br 2 O ROCH 2 COOEt Br O 1a,b 2a,b 1, 2 a R = Pr, b R = BuSuch compounds can be used as synthons for the synthesis of various spiro-fused butanolide-containing heterocycles, among which highly biologically active compounds [8,9] and also natural compounds of plant origin [10,11] have been found.In fact, in the reaction of equimolar amounts of the bromides 2a,b with thiocarbamide or its monoarylsubstituted derivative in dry acetone under mild conditions (20°C for 1 h, boiling for 1 h) high yields of previously undescribed spiroheteryl-fused butanolides with a new structure, 8

Efficient synthesis of 5‐(2‐hydroxyethyl)‐2‐phenylimino‐ 1,3‐thiazolidin‐4‐ones and 5‐(2‐hydroxyethyl)‐2‐phenylamino‐4,5‐dihydro‐1,3‐thiazol‐4‐ones

“…Similar method [9] starting from substituted phenylthioureas and ethyl 3‐bromo‐5‐methyl‐2‐oxo‐tetrahydrofuran‐3‐carboxylate, ethyl 3‐bromo‐5,5‐dimethyl‐2‐oxotetrahydrofuran‐3‐carboxylate, and ethyl 3‐bromo‐5‐isobutoxymethyl‐2‐oxotetrahydrofuran‐3‐carboxylate giving spirocyclic 2‐aza‐3‐amino or substituted amino‐4‐thia‐7‐oxa‐8‐methyl‐8‐substituted spiro[4.4]‐2‐nonene‐1,6‐diones was recently published. In this case, nitrogen atom of isothiuronium salt attacks ethoxycarbonyl group in position 3 instead of lactone carbonyl group.…”