- One-electron Oxidation of 2,2-dimethyl-2-silaindane by Potassium 12-Tungstocobaltate(III). Lack of Evidence for Stereoelectronic Effects on the Cleavage of a β-Carbon-Silicon Bond in an Aromatic Cation Radical
-
The one electron transfer oxidation of 2,2-dimethyl-2-silaindane by K5CoIIIW12O40 leads, in a slow step, to a radical cation which then undergoes fast C-Si bond cleavage, thus indicating that the rate of this cleavage is not significantly affected by the orientation of the C-Si bond with respect to the aromatic system.
- Baciocchi, Enrico,Bernini, Roberta,Lanzalunga, Osvaldo
-
p. 1691 - 1692
(2007/10/02)
-
- The Transformation of Cyclic Alcohols into Cyclic Acetals through a New Oxygen Atom Insertion by Photolysis in the Presence of Lead Tetraacetate and Iodine
-
Photolysis of the hypoiodites of steroidal cyclic homoallyl alcohols such as cholesterol and of cyclic alcohols such as 5α-androstan-17β-ol generated in situ in bnezene with three molar equivalents each of lead tetraacetate and iodine was found generally to result in the unprecedented formation of corresponding lactol acetates in yields up to 66percent.The lactol acetates are readily hydrolysed to lactols in most cases during their isolation and lactols are isolated products.Thus, cholesterol gave 4-oxa-A-homocholest-5-en-3-ol and its acetate in a 53percent yield.The products differ considerably from those reported by us after the photolysis of the hypoiodites by using mercury(II) oxide and iodine as the reagents for generating the hypoiodites; they also differ from those in the oxidation of the steroidal alcohols with lead tetraacetate alone.The photolysis of the hypoiodite of 2,2-dimethyl-5β-cholestan-3-ol was found to lead to the formation of an anomaluos lactol, 2α-iodomethyl-2β-methyl-4-oxa-A-homo-5α-cholestan-4ξ-ol together with normal lactol.We discuss the paths of the formation of the lactol acetates involving β-scission of the alkoxyl radicals.A new process was found in the photolysis of 2-indanol hypoiodite in the presence of lead tetraacetate and iodine.Our previously suggested pathways to the formation of 3α,5-epoxy-6-iodo-4-oxa-A-homo-5α-cholestanes and 3-formyloxy-2-iodo-2,30seco-A-norcholest-5-ene in the photolysis of cholesterol hypoiodite in the presence of mercury(II) oxide and iodine were supported by the results of the photolysis of 4-oxa-A-homocholest-5-en-3-ol hypoiodite in the presence of mercury(II) oxide and iodine were supported by the results of the photolysis of 4-oxa-A-homocholest-5-en-3-ol hypoiodite in the presence of mercury(II) oxide and iodine.
- Suginome, Hiroshi,Washiyama, Haruka,Yamada, Shinji
-
p. 1071 - 1084
(2007/10/02)
-
- Formation of Cyclic Carbonates in the Reaction of 1,2-Ditertiary Diols with Acetic Anhydride and 4-(Dimethylamino)pyridine
-
The reaction of 1,2-ditertiary diol 1a with acetic anhydride and 4-(dimethylamino)pyridine (DMAP) at high concentrations in the absence of solvent has been found to give rise to cyclic carbonate 2a.The reaction has been generalized with a few other 1,2-ditertiary diols (1b-d).Based on the different products isolated in these reactions, apart from a small amount of normal acetylation products, various mechanisms have been proposed and examined.Tertiary alcohols have been found to give monoacetoacetates in addition to the acetates, under the same conditions.Detailedinvestigations have prompted us to suggest the intermediacy of ketene and diketene in these reactions.
- Bhushan, Vidya,Chakraborty, Thushar K.,Chandrasekaran, Srinivasan
-
p. 3974 - 3978
(2007/10/02)
-
- Reactions of Benzotelluracyclopentane Diiodide
-
Benzotelluracyclopentane diiodide (1) and the derivatives of the general formulate C8H8TeX2 (X=halide, pseudohalide, carboxylate) and +- (R=alkyl; X=halide) have been synthesized and characterized.I reacts with Na2S*9H2O to give C8H8Te which undergoes oxidative addition reactions yielding C8H8TeXY (XY=halogen, interhalogen, organic halide, N-bromosuccinimide or benzamide) and molecular adducts with HgCl2 and Cu2Cl2.Te-C (alkyl) and Te-N bonds are readily cleaved by electrophiles.The elemental analysis, molar conductance, uv, ir, pmr and tga data are presented in support of the structure of newly synthesized compounds.
- Srivastava, T. N.,Srivastava, P. C.,Kumar, Rakesh
-
p. 186 - 190
(2007/10/02)
-