Reaction of N-substituted thioamides with gem-dicyano epoxides: a new synthetic route to anhydro-4-hydroxythiazolium hydroxides

Experimental and theoretical study of the [3 + 2] cycloaddition of carbonyl ylides with alkynes

“…Oxiranes were prepared according to the described procedures. 9 Toluene was dried before use. Reactions were performed under dry argon.…”

A Combined Experimental and Theoretical Study of the Polar [3 + 2] Cycloaddition of Electrophilically Activated Carbonyl Ylides with Aldehydes and Imines

“…Reactions were first carried out between 2,2-dicyano-3-(4-substituted)phenyloxiranes 1a-c 10 and benzaldehydes 2 (1 molar equivalent) in order to get 2,5-diphenyl-1,3-dioxolane-4,4-dicarbonitriles (Table 1). The conversion to the derivatives 3-5 using 3,4,5-trimethoxybenzaldehyde (2a) was monitored by NMR, and showed that the reactions carried out in refluxing toluene were completed after 35-68 h, depending on the R 1 group on the epoxide 1.…”

“…The products 16b-17b were identified using 1 H and 13 C NMR spectra of enriched fractions, and 18b from the 1 H NMR spectra of the crude mixture. When furan-2-carboxaldehyde (11) (Entries 7-9) and thiophene-2-carboxaldehyde (12) (Entries [10][11][12] were similarly involved in the reactions with 2,2-dicyano-3-(4-substituted)phenyloxiranes 1a-c, 10 rather similar a:b ratios were obtained, that is to say 66/34 (19, Reactions were finally carried out between 2,2-dicyano-3-(4-substituted)phenyloxiranes 1a-d 10 and imines 25 15 (1 molar equivalent) in order to get substituted 2,4-diphenyloxazolidine-5,5-dicarbonitriles (Table 3). The conversion to the derivatives 26-28 using N-(phenylmethylene)methanamine (25a), 30-32 using N- (1,3-benzodioxol-5-ylmethylene)propylamine (25b), 34-36 using N- (1,3-benzodioxol-5-ylmethylene)butylamine (25c), and 38-40 using N- (1,3-benzodioxol-5-ylmethylene) (18-40%).…”

Non‐Dipolar Behavior of Mesoionic Heterocycles: Synthesis and Tautomerism of 2‐Alkylthioisomünchnones

“…These results provide the first evidence of differential reactivity of the tautomeric species of a mesoionic heterocycle. It is fair to say that the equilibrium between a 2‐methylthioisomünchnone derivative and its tautomer, the 2‐methylenethiazolidin‐4‐one, had been detected previously by Baudy et al through IR and NMR monitoring 11. Moreover, valence tautomers in mesoionic chemistry have long been sought.…”