Showing papers by "Masahiro Murakami published in 1994"

Selective activation of carbon–carbon bonds next to a carbonyl group

Abstract: ORGANOMETALLIC complexes are used to effect a wide range of catalytic transformations in organic synthesis, such as the activation of C–H bonds1,2. Carbon–carbon bonds, however, are generally unreactive towards transition metals under homogeneous conditions. C–C bond activation by a process of oxidative addition to soluble transition-metal complexes has been limited mostly to stoichiometric (not catalytic) reactions1,3–7,18, to highly strained substrates such as cyclopropane and cubane1,8–11or to chelating ketones19. Here we present a synthetically useful process of selective C–C bond activation in which the C–C bond adjacent to a carbonyl group is opened by insertion of a soluble rhodium(I) complex. The resulting organometallic intermediate can be transformed to a variety of products in a way that regenerates the rhodium complex. We anticipate that this catalytic scheme will have considerable utility in organic synthesis.

Stereoselective Synthesis of 2-Amino Alcohols by Use of an Isocyanide as an Aminomethylene Equivalent.

Abstract: Preparation of an isocyanide having a removable N-substituent and its application to the stereoselective synthesis of 2-amino alcohols are described. 4-(tert-Butyldimethylsiloxy)-2,6-xylyl isocyanide was prepared from commercially available 3,5-xylenol. The isocyanide underwent a samarium iodide-mediated coupling reaction with organic halides and carbonyl compounds. Reduction of the reaction mixture with NaBH 4 selectively afforded anti 2-(arylamino) alcohols, which were then deprotected to the corresponding 2-(primary amino) alcohols via desilylation with TBAF followed by oxidation with DDT. A ceramide was successfully synthesized by use of the present stereoselective synthetic method for 2-amino alcohols, demonstrating a new synthetic utility of the isocyanide as an aminomethylene equivalent