Formation and Reactions of Novel Heterocycles: 1,3,4-Oxadithiolane, 1,3,4-Oxadiselenolane, 1,3-Oxathietane, and 1,3-Oxaselenetane Derivatives

Abstract

The reactions of 2,2,4,4-tetramethyl-1,5-diphenyl-1,5-pentanedione monohydrazone with S2Cl2 and Se2Cl2 gave 2,2,4,4-tetramethyl-1,5-diphenyl-8-oxa-6,7-dithiabicyclo[3.2.1]octane (9) and 2,2,4,4-tetramethyl-1,5-diphenyl-8-oxa-6,7-diselenabicyclo[3.2.1]octane (10), respectively. Dechalcogenation of 9 or 10 with triphenylphosphine in boiling toluene yielded an equilibrium mixture of 2,2,4,4-tetramethyl-1,5-diphenyl-6-oxa-7-thiabicyclo[3.1.1]heptane (11) and 2,2,4,4-tetramethyl-1,5-diphenyl-5-thioxo-1-pentanone (13) or 2,2,4,4-tetramethyl-1,5-diphenyl-6-oxa-7-selenabicyclo[3.1.1]heptane (12), respectively. On the other hand, the reaction of 10 with hexamethylphosphorous triamide [P(NMe2)3] in boiling toluene gave 12, 3-methyl-3-(2,2-dimethyl-3-oxo-3-phenylpropyl)-2-phenylselenetanes (18), 5-benzoyl-3,3,5-trimethy1-2-phenylselenanes (19), 6,6,8,8-tetramethyl-9-phenyl-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-one (20), and 3,3,5,5-tetramethyl-1,2-diphenylcyclopentene (21), while that of 9 afforded 11, 13, 3-(2-benzoyl-2-methylpropyl)-3-methyl-2-phenylthietanes, 20, and 21. The reaction of 12 with P(NMe2)3 also gave 18, 19, 20, and 21. A single-electron transfer mechanism seems to be operative in the reaction of 9 or 10 with P(NMe2)3. Compounds 11 and 13 are in equilibrium with each other at room temperature, while a ring-opening of 12 to 2,2,4,4-tetramethyl-1,5-diphenyl-5-selenoxo-1-pentanone is observed on heating by the UV-vis and 1H NMR spectra.

Four‐Membered Heterocycles: Structure and Reactivity

“…A selenetane has been prepared in low yield by reaction of a diseleno compound with hexamethylphosphotriamine (Scheme 3.214) [380]. The 1,3-oxaselenetane derivative was obtained in 72% yield when the reaction was carried out in the presence of triphenylphosphine.…”