A Thio-Staudinger Reaction: Thermolysis of a Vinyl Azide in the Presence of t -Butyl Mercaptan

Abstract

The thermal decomposition of E-3-azido-3-hexene-2,5-dione (1) in protic media gave rise to several novel reactions of the azide 1 including adducts derived from keteneimine 11. Reaction with t-butyl mercaptan yielded two products, keteneimine-derived mercaptan addition product 20 and a sulfenimine 6. Trapping of a vinyl nitrene intermediate or a thio-Staudinger reaction was considered as a possible mechanism for the formation of sulfenimine 6. The absence of the vinyl nitrene addition products 3 and 5 when the thermal decomposition was conducted in either methanol or t-butylamine suggests a thio-Staudinger reaction is operative.

γ-Hydroxyalkynyl Ketones as Useful Scaffolds for the Preparation of Combinatorial Libraries of Furans, Isoxazoles and Pyrazoles

“…Following the methodology developed by Hassner, two different methods were initially evaluated for the synthesis of (E)-3-azido-3-hexene-2,5-dione (3). One approach involved the addition of iodoazide to either (Z)-or (E)-3hexene-2,5-dione (1 and 2), followed by elimination to yield only (Z)-3-azido-3-hexene-2,5-dione (4). 15 The other approach involved the reaction of a mixture of (E)-and (Z)trans -3-bromo-3-hexene-2,5-dione (5 and 6) with sodium azide, to exclusively afford only the Z isomer 4.…”

“…In recent years, several different approaches for the preparation of combinatorial libraries of heterocycles have been described. 1,2 Using chemistry that we developed for the synthesis of (E)-3-azido-3-hexene-2,5-dione (3), 3,4 we wish to illustrate the applicability of this methodology for the preparation of combinatorial libraries of furans 5 and isoxazoles 6 and also to illustrate the utility of the γ-hydroxyalkynyl ketone scaffold for the preparation of pyrazole libraries. 7 γ-Hydroxyalkynyl ketones are useful starting materials for the preparation of 3-halofurans, 8 3-methoxyfurans, 9 furonones, 9 3-thiolfurans 10 and 3-furylcarbonyl compounds.…”

1,4‐Conjugate Additions of Methoxyamine and 1,1‐Dimethylhydrazine to Hex‐3‐yne‐2‐one: A Facile Synthesis of Functionalized Isoxazole and Pyrazole Precursors

“…calcd. for C 7 H 11 NO 3 Preparation of the 3-(N,N-dimethylhydrazone) of 2,3,5-hexanetrione (7). To a solution of 2.21 g (0.02 mol) of hex-3-yne-2,5-dione (2) [6] in 50 mL of carbon tetrachloride, which had been cooled to 210 8C, 1.53 mL (0.02 mol) of 1,1-dimethyl hydrazine in 10 mL of carbon tetrachloride was added over a 15-min period.…”

“…This method is a general way to prepare these heterocycles, but unsymmetrically substituted 1,3-diketones will yield a mixture of compounds and the method would not be tolerant of additional reactive functionality. [1] During the course of study on the photochemistry of 3-acetyl-5-methylisoxazole (5), [2] we synthesized and evaluated the chemistry of the related Z-and E-3-azido-hex-3-ene-2,5-dione [2,3] and also routinely characterized photoproducts by independent synthesis. These investigations led us to examine the chemistry of substituted alkynyl ketones.…”

Sulfonyl and Phosphoryl Azides: Going Further Beyond the Click Realm of Alkyl and Aryl Azides

“…On the basis of the previously reported synthetic procedures,18 amidine compounds could be independently prepared by starting from N ‐sulfonyl amides presumably through a ketenimine intermediate. It is well known that alcohols or water readily react with ketenimines to lead to imidates19 or amides 20. It was observed that when ( N ‐tosyl)phenylacetamide ( 7 ) was treated first with PPh 3 Br 2 in the presence of triethylamine and then treated with diisopropylamine, the corresponding amidine 3 was obtained in good yield [Eq.…”