96745-90-3Relevant academic research and scientific papers
THE TRANSIENT DIENOPHILE DIETHYL THIOXOMALONATE AND ITS S-OXIDE (SULPHINE) FORMED BY RETRO-DIELS-ALDER CLEAVAGE REACTIONS
Kirby, Gordon W.,McGregor, William M.
, p. 3175 - 3181 (2007/10/02)
Diels-Alder adducts 3 and 4 of diethyl thioxomalonate 1, formed from diethyl oxomalonate (mesoxalate) and phosphorus pentasulphide, with cyclopentadiene and anthracene, dissociate at 111 0C to release the reactive thioketone 1.This was trapped in situ with 2,3-dimethylbuta-1,2-diene to give the corresponding cycloadduct 2.Similarly, the thioketone 1 reacted with 2-trimethylsiloxybuta-1,3-diene 8 to form only the 5-trimethylsiloxythiine 13, and with β-pinene 16 to form only one 'ene' product 17b, with C-S bond formation.The S-oxide 19 of the anthracene adduct 4 and the exo-S-oxide 27 of the cyclopentadiene adduct 3 likewise dissociatedthermally to release the corresponding sulphine, diethyl thioxomalonate S-oxide 21, wich was trapped in situ as the dimethylbutadiene adduct 23.The exo-sulphoxide 27, when heated alone, gave the sultene 29, presumably via -sigmatropic rearrangement of the transient endo-sulphoxide 28.The sulphine 21, generated by flash vacuum pyrolysis of the anthracene adduct 19, reacted at low temperature with cyclopentadiene to give the exo-sulphoxide 27, and with water to give diethyl malonate.
