No abstract

2005 Cycloalkylphenyl derivatives Q 0760 Stereoselective Preparation of Spiran-Bridged, Sandwiched Bisarenes. -The synthesis of dioxospirans (III), (V), and (XVI) is presented. The former is prepared by a new synthetic route. The products are transformed into vinyl triflates which smoothly undergo Pd-catalyzed cross-coupling under Stille, Suzuki, or Negishi conditions to afford the title compounds. Hydrogenation of the unsaturated molecules proceeds with high stereoselectivity. -(ROLANDSGARD, M.; BALDAWI, S.; SIRBU, D.; BJOERNSTAD, V.; ROEMMING, C.; UNDHEIM*, K.; Tetrahedron 61 (2005) 16, 4129-4140; Dep. Chem., Univ. Oslo, N-0315 Oslo, Norway; Eng.) -Jannicke 34-126

a-Oxospiranes have been converted into vinyl triflates for phosphorylation and arylation by palladium-catalyzed crosscoupling reactions. With diethyl phosphite, the coupling provided olefinic mono-and diphosphonated spiranes. Saturation of conjugated aryl and phosphonyl alkene bonds was stereoselective when effected by catalytic hydrogenation. The double bond in conjugated alkenylphosphonates was in general more difficult to reduce than conjugated aryl derivatives. In mixed substrates, regioselectivity in the saturation of conjugated olefinic bonds was obtained.

Organo-phosphorus compounds S 0080Stereoselective Synthesis of α-Phosphorylated Spirans. -(ROLANDSGARD, M.; BJOERNSTAD, V.; UNDHEIM*, K.; Synthesis 2007Synthesis , 18, 2803Synthesis -2808 Dep. Chem., Univ. Oslo, N-0315 Oslo, Norway; Eng.) -Jannicke 08-174