Shaun T. E. Mesher

Montmorillonite K10/ZnCl2 Catalyzed Alkyl Disulfide Substitution Reactions: Preparation of Thiomethyl Derivatives for the Synthesis of Organic Conducting Materials

Experiments are described detailing a method for the direct introduction of thiomethyl groups into activated benzenes, thiophene and benzo[b]thiophene using an activated mesoporous clay to promote thiomethyl substitution. Elaboration of 2,3-dithiomethylbenzo[b]thiophene, a product of the clay-catalyzed reaction of benzo[b]thiophene with dimethyl disulfide, to a tetrathiafulvalene derivative is described.

Unexpected thermal extrusion of CO2 from 3-benzylthiazolidin-2-one 1,1-dioxides to give 2-phenylthiazolines and thiazoles

Abstract Flash vacuum pyrolysis of a series of chiral 3-benzylthiazolidin-2-one 1,1-dioxides 5 , readily prepared from amino acids, results mainly in loss of SO 2 to give an alkene and benzyl isocyanate, but a significant minor pathway involves unexpected loss of CO 2 and water to give 2-phenylthiazolines 13 and derived thiazoles.

KINETIC RESOLUTION OF SECONDARY ALCOHOLS USING PROLINE-DERIVED BICYCLIC IMINIUM SALTS

The proline-derived bicyclic iminium salt 3 can be used to bring about kinetic resolution in its reaction with salts of secondary alcohols to give the corresponding methyl sulfides. Reaction proceeds most efficiently with sodium 1-phenylethoxide in toluene at RT where either 3 or the bezyl salt 14 give e.e.s of 21–25% and changing the heteroatoms present in the salts, the metal cation used and the solvent and temperature all give similar or lower lelectivity.

Natural abundance 33S NMR spectroscopy. The first spectra of several major compound types

Using a high field, high power instrument, 33S NMR spectra have been obtained for several previously unobservable compound types including an aromatic isothiocyanate, a thiocyanate, a thiophenol, an alkyl aryl sulfide, a thiazole, a persulfate, a sulfinic acid and sulfinate salts, a sulfonhydrazide and a sulfinyl halide. The range of data for sulfonyl fluorides and chlorides has also been extended considerably.

Synthesis and oxidation of chiral 2-thiazolines(4,5-dihydro-1,3-thiazoles)

Eight new chiral 2-thiazolines (4,5-dihydro-1,3-thiazoles) 2 have been prepared by treatment of the 2-methyloxazolines 1, the benzoylamino alcohols 4 or the trimethylacetylamino alcohols 5 with P2S5. With a 2-methyl substituent, reaction with Oxone® results in ring-opening to give the acetylamino disulfides 9 and with MCPBA there is also ring-opening with incorporation of a m-chlorobenzoyl group to give 12. Treatment of the 2-phenyl compounds with a variety of oxidants gives the benzoylamino sulfonic acids 10 and the disulfides 9 together with the thiazoles 11 in varying proportions. The sulfonic acids and thiazoles are obtained in pure form by reaction with 3 equiv. of peracetic acid and with sulfur, respectively. Although reaction of 2d–f with KMnO4 under phase-transfer conditions gives the thiazoles 11, addition of 1 equiv. of benzoic acid results in a complete change in selectivity to afford the thiazoline 1,1-dioxides 3d–f in excellent yield. These compounds prove to be exceptionally moisture-sensitive and readily hydrolyse to give the benzoylamino sulfinic acids 8 whose further oxidation and disproportionation probably explains the formation of the sulfonic acids and disulfides with the other oxidants. The high reactivity of the sulfones 3 towards nucleophilic ring-opening precludes their deprotonation and alkylation. Upon flash vacuum pyrolysis at 600 °C, they fragment to give SO2, benzonitrile and the alkenes 16 in high yield. Fully assigned 13C NMR spectra are presented for the 18 heterocyclic compounds prepared and for 17 acyclic derivatives.

Synthesis and pyrolytic behaviour of thiazolidin-2-one 1,1-dioxides

Four examples of the chiral thiazolidin-2-one 1,1-dioxides 5 have been prepared by reaction of the appropriate amino alcohols 11 with CS2 in aqueous sodium hydroxide to give the thiazolidine-2-thiones 12, followed by oxidation with KMnO4 under phase-transfer conditions in the presence of benzoic acid, either directly or via the thiazolidin-2-ones 13. Upon flash vacuum pyrolysis (FVP) at 650 °C, 5a–c decompose mainly by loss of SO2 to give an alkene and benzyl isocyanate together with other products from fragmentation of the N-benzyl group. A significant minor pathway involves net loss of CO2 and water to give the 2-phenyl-4,5-dihydrothiazoles 21 together with their aromatisation products 22 and 23. A mechanism for this new heterocyclic transformation is proposed involving initial expansion to a cyclic carbamic–sulfinic anhydride (2,1,4-oxathiazin-3-one 1-oxide). The fully assigned 13C NMR spectra are presented for 5, 12 and 13 and the 33S NMR spectrum has been obtained for 5c.

Synthesis and Pyrolytic Behaviour of Chiral Thiazolidine 1,1-Dioxides

Five chiral thiazolidine 1,1-dioxides have been prepared and the pyrolytic behaviour of this class of compound has been examined for the first time.

Chiral thiazolidine-2-thione derived iminium salts as reagents for kinetic resolution

Abstract There are currently few simple reagent systems available which can effect efficient kinetic resolution of racemic compounds. We report here a series of chiral bicyclic iminium salts, which can resolve racemic secondary alcohols to give both the unreacted alcohol and the sulphide resulting from reaction in moderate enantiomeric excess.