The reaction between bis(trialkyltin) chalcogenides and trimethylaluminum results in the formation of bis(dimethylaluminum) chalcogenides, (Me2Al)2E, where E is S, Se, or Te. Reaction between the latter and carbonyl groups (but not carboxylic acids or esters) converts them to carbon−chalcogen double-bond (CE) compounds. Using this procedure, we have successfully synthesized several telluro- and selenocarbonyl compounds. The first successful synthesis of an isolable, crystalline telluroformamide, 4-(telluroformyl)morpholine (3c, C5H9NOTe), and its crystal structure are reported. Also, the syntheses and crystal structures of a γ-tellurolactam, 1-methyl-2-telluroxopyrroline (3d, C5H9NTe), and two selenoamides, N,N-diphenylselenoformamide (3a, C13H11NSe) and N-methyl-N-(4-nitrophenyl) selenoformamide (3b, C8H8N2O2Se) are described.

No abstract

Phthalocyanine ruthenium complexes were identified as red-light activatable catalysts for trifluoromethylation reactions.

The Arbuzov reaction of (2S,4S)-4-methyl-2-phenyl-1,3,2-dioxaphosphorinane with various alkyl halides gave the diastereomerically pure phosphinates with regioselective cleavage of the primary carbon–oxygen bond. These phosphinates reacted with Grignard reagents to give optically active phosphine oxides in high optical yields.

No abstract

The reactions of alpha,beta-unsaturated aldehydes and ketones with bis(dimethylaluminum) selenide, (Me(2)Al)(2)Se, yield the corresponding alpha,beta-unsaturated selenoaldehydes and selenoketones. They are too unstable to be isolated in the monomeric form, but they undergo regioselective [4 + 2] dimerization via a "head-to-head" oriented transition state to afford diselenin derivatives (trans and cis isomers). Theoretical calculations at the density functional theory level show that this selectivity occurs because the "head-to-head" dimerization is thermodynamically favored over the "head-to-tail" by about 14 kcal/mol. Both dimerization reactions have low energy barriers: 1.5 and 2.8 kcal/mol for the former and 0.9 and 1.3 kcal/mol for the latter. In the presence of norbornadiene, these compounds function as 4pi heterodienes (C=C-C=Se) to give the respective cycloadduct products. On the other hand, they act as 2pi dienophiles (C=Se) in the reactions with cyclopentadiene except for selenoacrolein which serves as a 4pi diene and only one C=C bond (2pi) in cyclopentadiene is involved in the reaction. Theoretical calculations have been carried out in order to better understand these observations.

Alpha,beta-unsaturated thioaldehydes and thioketones, R1CH=CH-C(=S)R2, are prepared in situ by the reaction between the corresponding carbonyl compounds and bis(dimethylaluminum) sulfide. These compounds undergo [4 + 2] self-dimerization reactions in which one molecule serves as the heterodiene component and the other as the dienophile to afford different types of dimeric products depending on the R1 and R2: 1,2-dithiin and 1,3-dithiin (R1 = R2 = H), 1,2-dithiin (R1 = Ph, R2 = H, CH3), or dihydrothiopyran (R1 = R2 = Ph). These differences in selectivity are explained on the basis of the relative energies evaluated by molecular orbital (MO) calculations at the DFT (density functional theory) level. The calculations show that in the dimerization reaction of thioacrolein (I), the head-to-tail (S-C-S bonded) dimers are kinetically more stable by about 5 kcal/mol but slightly thermodynamically unstable by about 2 kcal/mol than the head-to-head (S-S bonded) dimers. The calculations on thiocinnamaldehyde (IV) indicate that the dimerization reactions of phenyl-substituted alpha,beta-unsaturated thioaldehydes and thioketones are almost equally controlled by thermodynamic and kinetic factors. These unsaturated thiocarbonyl compounds also function as heterodienes (C=C-C=S) in the cycloaddition reaction with norbornadiene and as dienophiles (C=S) in the reaction with cyclopentadiene.

The Arbuzov reaction of (5S,6S)-dimethoxy-2-phenyl-1,3,2-dioxaphosphacycloheptane with various alkyl halides produced acyclic phosphinates in a moderate to high diastereomer excess. The same reaction of (1S,7S)-9,9-dimethyl-4-phenyl-3,5,8,10,4-tetraoxaphosphabicyclo[5.3.0]decane with the alkyl halides needed the more vigorous reaction conditions and gave phosphinates in a low diastereomer excess. These phosphinates were converted into optically active phosphine oxides.