Thiiranes, chiral—

The configurations of chiral thiiranes and thiirane 1-oxides can be determined by H NMR experiments in chiral solvents such as (R)-(-)- -phenyl-2,2,2-trifluoroethanol. The... 

The 260 nm band of chiral thiiranes is optically active and a Cotton effect is observed R) (+)-methylthiirane shows a negative Cotton effect at ca. 250 nm followed by a positive effect below 200 nm. An MO analysis indicates that charge transfer contributions are most important in determining the optical activity of the transition (81JCS(F2)503). The... 

Treatment of cyclic carbonates of 1,2-diols with thiocyanate ion at temperatures of 100 °C or higher yields thiiranes (Scheme 145) (66CRV297, 75RCR138). Thiourea cannot replace thiocyanate satisfactorily, and yields decrease as the carbonate becomes more sterically hindered. The reaction mechanism is similar to the reaction of oxiranes with thiocyanate (Scheme 139). As Scheme 145 shows, chiral thiiranes can be derived from chiral 1,2-diols (77T999, 75MI50600). 

Chiral polymer-supported thiiranes 401 were prepared by free radical copolymerization of TMA ((3)-thiiranylmethyl-methacrylate) and ethylene glycol dimethacrylate (EDMA) (Equation 60) <2006TA1944>. These chiral thiiranes were transformed into polymer-supported aminothiols by the facile ring opening of the thiirane group with benzylamine and methylamine. These derivatives, complexed with [RuCl2(p-cymene)]2, were used in assymmetric reduction of acetophenone to gave (A)-l-phenylethanol (39% ee from methylamine and 50% ee from benzylamine derivatives). 

General Reactions.—A full account of the synthesis of thiirans from aldehydes and ketones using metalated 2-(alkylthio)-2-oxazolines has appeared. Asymmetric syntheses of chiral thiirans can be effected using either a chiral oxazoline or a chiral dialkyl dithiocarbonate. ... 

A simple synthesis of chiral thiiran carboxylic acids from cysteine derivatives has been described by Maycock and Stoodley. Diazotization of methyl (if)-cysteinate (106) gave (107), whilst under the same conditions (i )-cysteine (108) gave a mixture of the (5) and R) enantiomers (109) and (110). 

The photoelectron spectrum of thiiran 1-oxide has been reported, and orbital-correlation diagrams have been constructed. The c.d. spectra of some chiral thiiran 1-oxides have been determined. ... 

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