A novel route towards formylated 1,3-dithiole-2-thiones via an unprecedented allylic 1,4-diol rearrangement

Abstract

In the presence of perchloric acid, an unusual 1,4-aryl shift is observed for two electron-rich 4,5-bis[hydroxy(aryl)methyl]-1,3-dithiole-2-thiones; the X-ray crystal structure of compound 8 confirms the structural identity of the rearrangement product

Cover Picture: Controlling the Chair Conformation of a Mannopyranose in a Large‐Amplitude [2]Rotaxane Molecular Machine (Chem. Eur. J. 21/2009)

“…Similar changes can also be found in the two transition states TS‐DE and TS‐EF . These results indicate that the p ‐methoxy group has a great effect on the stabilization of the phenonium intermediate and the transition states involved, as proposed by Tahir Khan et al 9a…”

Redox-active tetrathiafulvalene and dithiolene compounds derived from allylic 1,4-diol rearrangement products of disubstituted 1,3-dithiole derivatives

“…One possible explanation for this can be derived from the X-ray crystal structure of the dihydrofuran derivative [4]. The intramolecular close contacts between O(2)···S(2) and O(3)···S(3) arise from a three-centre four-electron interaction [15], which decreases the electron releasing ability of the methoxy groups towards the benzene ring, thereby conferring a weaker stabilising effect upon the phenonium ion.…”

“…It is also unusual that the sole product from the corresponding 2-methoxyphenyl compound leads to a dihydrofuran derivative, particularly since the electron donating substituent effect should be identical to that of the 4-methoxy compound, which rearranges to give the corresponding dihydrofuran. One possible explanation for this can be derived from the X-ray crystal structure of the dihydrofuran derivative [ 4 ]. The intramolecular close contacts between O(2)···S(2) and O(3)···S(3) arise from a three-centre four-electron interaction [ 15 ], which decreases the electron releasing ability of the methoxy groups towards the benzene ring, thereby conferring a weaker stabilising effect upon the phenonium ion.…”

“…2 ). In each case, the addition of perchloric acid resulted in a complex mixture of products, which could not be easily separated [ 4 ].…”

“…Our efforts to prepare triaryl derivatives of compound 1 led to the discovery of an unexpected rearrangement of 4,5-bis(2-arylhydroxymethyl)-1,3-dithiole-2-thiones ( 2 ) in the presence of acid catalysts [ 4 ]. As well as the expected dihydrofuran, formed by a nucleophilic ring-closing reaction, other compounds were also produced depending on the nature of the aryl group, the nature of the solvent and the acid used (e.g., 3 ).…”