Polydonor-Substituted 1-Oxa- and 1-Thia-3,5-diazahexatrienes: Synthesis, Structures, Ring−Chain Tautomerism and Theoretical Calculations

Abstract

Previously unknown 1-oxa-2,4-diazahexatrienes 1a,b and c, substituted with alkoxy groups, have been prepared by carboxylation of N-alkylideneisoureas 2 with chloroformates 5. Xray analyses of compounds 1b and c show nonplanar, openchain structures. In contrast, thiocarboxylation of 2 with thiochloroformate 6 leads to the spiro compounds 7-ring, as verified by spectroscopic data and X-ray analysis. A tetradonor-substituted 1-oxa-2,4-diazahexatriene 1d was obtained from the reaction of the 1-oxa-3-aza-butadiene 10 with the triply donor-substituted carbenium ion 9. Attempts at further chain elongation of 1a by an alkylation/condensa-

The antifungal agent methyl 2-benzyl-6-diethylamino-4-phenyl-2H-1,3,5-thiadiazine-2-carboxylate

“…The SÐC distances are S1Ð C5 = 1.752 (3) A Ê and S1ÐC7 = 1.849 (3) A Ê . This is in agreement with the distances observed previously (Maier et al, 2001) in a similar compound, also containing a 1,3,5-thiadiazine nucleus. While the phenyl substituent is essentially in the plane of the corresponding C6 N3 bond, the benzyl group is twisted by 112.8 (3) (C16ÐC11ÐC10ÐC7) out the plane of the heterocyclic ring.…”

Radical Cyclization of N‐Acylcyanamides: Total Synthesis of Luotonin A

“…Synthesizing the N ‐acylcyanamides substrates was challenging: the preparation of N ‐acetyl‐ and N ‐benzoylcyanamides and some of their derivatives has been reported, but those molecules often show a lack of stability 12–15. As N ‐acylcyanamides display properties in other fields, for instance, as prodrugs of cyanamide,13 enzymatic inhibitors16 and heteroanalogues of ethylenes,17 there is also an interest in their practical synthesis. We report herein the preparation of stable N ‐acyl‐ N ‐(2‐iodobenzyl)cyanamides and their use as radical partners in cyclization cascade processes, which led to the total synthesis of luotonin A.…”