SMe Group Research Articles

The crystal and molecular structure of η 5-cyclopentadienyliodomethyl(methylthio)carbene-(triphenylphosphine)iridium(III) iodide

The crystal and molecular structure of η 5-cyclopentadienyliodomethyl(methylthio)carbene(triphenylphosphine)iridium(III) iodide [IrI{C(Me)SMe}(η 5-C 5H 5)(PPh 3)]I has been determined from three dimensional X-ray data in order to clarify the contribution of the α-sulphur atom to the bonding in this carbenoid complex. The compound crystallizes in space group Pbc2 1 with four formula units in a cell of dimensions a 9.745(6), b 15.201(8), and c 17.364(10) Å. Least-squares refinement of the structure has led to the final discrepancy index R = 0.047 for the 1655 symmetry-independent observable reflections. The coordination geometry about the iridium atom is approximately tetrahedral; the coordination positions are occupied by the η 5-C 5H 5 ring center, the phosphorus, the iodide I(1) and the carbon C(6) of the C(Me)SMe ligand (IrRc 1.89, IrP 2.280(7), Ir(1) 2.651(2) and IrC(6) 2.03(3) Å). The bonding of the C(Me)SMe group indicates that this complex must be formulated as a C(Me)SMe complex of iridium(III).

The thiolate anion as a nucleophile Part VIII. Reactions of dibromotetrafluorobenzenes

The reactions of the isomeric dibrometetrafluorobenzenes with the methanethiolate anion and copper(I) methanethiolate have been examined. Using the thiolate anion replacement of fluorine by the SMe group occurred, but with copper(I) methanethiolate protodebromination and replacement of the bromine with the SMe group occurred. The new compounds isolated have been characterized and their spectra (NMR, IR, and mass) examined.

Methyltropic tautomerism of the N–C–O and N–C–S groups: synthesis of methyl mono- and di-thiocyanurates

A number of well defined trimethyl mono- and di-thiocyanurates have been synthesised following a procedure which consists of two reactions, (i) nucleophilic substitution of an SMe group, bound to a substituted s-triazine ring, with an OMe group; and (ii) the thermal isomerisation of the product of reaction (i). Two reaction sequences are described whose starting compounds are respectively the unsymmetric S,N,N-(1) and S,S,N-trimethyl trithiocyanurates (9). The corresponding dimethyl esters were obtained upon hydroysis of the products of reaction (i).Four trimethyl and two dimethyl dithiocyanurates; and four trimethyl and two dimethyl monothiocyanurates have been obtained and characterised; ten of them are reported for the first time.The rules of methyl migration in the thermal isomerisation, established in previous works, are confirmed and extended.

ChemInform Abstract: EFFECTS OF NEIGHBORING FUNCTIONAL GROUPS IN THE ASYMMETRIC REDUCTION OF Ω‐SUBSTITUTED ALKYL PHENYL KETONES WITH LITHIUM TRI‐L‐MENTHOXYALUMINUM HYDRIDE

AbstractDie enantioselektive Reduktion der Ketone (I) mit dem Reagenz (II) unter Bildung optisch aktiver Alkohole (III) wird hinsichtlich des Einflusses der funktionellen Gruppen Y (die Gruppe Y = Et dient als Vergleichsstandard) und der Anzahl n der Methylengruppen auf den Grad der Stereoselektivität untersucht.

Effects of Neighboring Functional Groups in the Asymmetric Reduction of ω-Substituted Alkyl Phenyl Ketones with Lithium Tri-l-Menthoxyaluminum Hydride

Abstract In the enantioselective reduction of ω-substituted alkyl phenyl ketones, PhCO(CH2)nY, with lithium tri-l-menthoxyaluminum hydride, the effect of the functional groups, Y(NR2, OMe, and SMe) on the stereoselectivity was examined in comparison with that of the alkyl group. Of the functional groups tested, the MeO group is more effective in enhancing the stereoselectivity than the NMe2 or SMe group except in the case of n=1. The optical yields are also affected by the number of the methylene group (n) in the substrates. These results strongly suggest that the coordination of the Y group with the reducing reagent is one of the essential factors in the stereoselectivity. The absolute configurations of the resulting alcohols are correlated with the relative magnitudes of the lanthanideinduced shifts(LIS) of their (+)-MTPA esters.

The Sn Mechanism in aromatic compounds. XXIII. Substituent groups attached by saturated sulphur

The activating power of p-SMe and p-SMe2+ in aromatic nucleophilic substitution has been compared with available data for ?NH2, -NMe3+, and OMe. The ?Sme2+; group is very powerfully activating and there is strong evidence for a -T effect of ?Sme2+ but not of -SMe, involving expansion of the valency shell beyond an octet. The -SMe group, like -Cl, -Br, and -I, is however also activating, whereas ?NH2, -OMe, and -F are more or less deactivating.