Reactions of Cycloaliphatic Thioketones and Their Oxo Analogues with Lithiated Methoxyallene: A New Approach to Vinylthiiranes

Abstract

Admantanethione smoothly reacted with lithiated methoxyallene at low temperatures yielding the expected allenyl-substituted thiolate, which upon aqueous work-up underwent spontaneous 1,3-cyclization to afford a hitherto unknown methoxy-substituted vinylthiirane derivative. The analogous reaction with adamantanone led to the corresponding allenyl alcohol that can be isolated and--depending on the conditions applied--either be converted into the corresponding vinyloxirane or into the 2,5-dihydrofuran derivative. Sterically more crowded thioketones were also combined with lithiated methoxyallene, but in these cases competitive 1,5-cyclization leading to isomeric dihydrothiophene derivatives was observed. DFT calculations of model intermediates and products show distinct energy differences of the sulfur and the corresponding oxygen compounds. Desulfurization of the adamantanethione-derived vinylthiirane yielded a methoxy-substituted 1,3-diene that was studied in cycloadditions with electron-deficient dienophiles. Whereas in the case of tetracyanoethylene the corresponding cyclobutane derivative was formed, the reaction with nitrosobenzene provided the expected 1,2-oxazine derivative. By reductive cleavage of the N-O bond this heterocycle was converted into an unsaturated amino alcohol bearing an adamantane moiety.

Stereospecific Reactions of Donor–Acceptor Cyclopropanes with Thioketones: Access to Highly Substituted Tetrahydrothiophenes

“…The hetero‐Diels–Alder reaction of thiocarbonyls with dienes is well explored, and various 2 H ‐thiopyrans have been obtained . Remarkably, the formation of five‐membered‐ring compounds from thioketones and a three‐carbon unit has rarely been reported …”

Metal Free Amino-Oxidation of Electron Rich Alkenes Mediated by an Oxoammonium Salt

“…Cleavage of the OACT group was then attempted so a crystalline derivative could be found, but this cleavage proved to be difficult. While the similar N-O ethers have been removed with many reagents (such as Zn/AcOH, 28 Zn/TMSCl, 29 Na(Hg) amalgam, 30 Raney Ni/H2, 31 Mo(CO)6, 32 SmI2, 33 and LiAlH4/NiCl2 34 ), the OACT group could only be removed in a moderate 43% yield with the LiAlH4/NiCl2 conditions. The other reagents mentioned gave <15% of the desired alcohol products, usually resulting in a complex mixture.…”

The Cyclization of Allenyl‐Substituted Hydroxylamines to 1,2‐Oxazines: an Experimental and Computational Study

“…[7] On the other hand, with related allenyl-substituted thiols a spontaneous formation of vinyl thiiranes was observed. [8] Scheme 1. Spontaneous 6-endo-trig cyclization of allenyl-substituted hydroxylamines A into 3,6-dihydro-2H-1,2-oxazines B.…”