Non-Carbonyl-Stabilized Metallocarbenoids in Synthesis: The Development of a Tandem Rhodium-Catalyzed Bamford−Stevens/Thermal Aliphatic Claisen Rearrangement Sequence
作者:Jeremy A. May、Brian M. Stoltz
DOI:10.1021/ja028020j
日期:2002.10.1
Bamford-Stevens/Claisenrearrangement is presented. The tandem reaction uses Eschenmoser hydrazones for the in situ generation of non-carbonyl-stabilized diazo alkanes, which are presumably intercepted by Rh(II) catalysts to induce a 1,2-hydride migration. This sequence provides high levels of stereocontrol for the generation of simple acyclic (Z)-enol ethers. These enol ethers undergo either thermal or Lewis
An efficient approach for the synthesis of 2,2-disubstituted indolin-3-ones is described. From readily accessible aryl hydrazines and allyloxyketones, 2,2-disubstituted indolin-3-ones could be obtained in good to excellent yields under mild reaction conditions via cascade Fischer indolization/Claisen rearrangement process. This protocol provides a facile entry to 2,2-disubstituted indolin-3-ones, which
Asymmetric [2,3]-sigmatropic wittig rearrangement of chiral α-allyloxy-hydrazones
作者:Dieter Enders、Dirk Backhaus、Jan Runsink
DOI:10.1016/0040-4020(95)00982-5
日期:1996.1
[2,3]-Wittig rearrangement of chiral α-allyloxy-hydrazones (S)-3 and (S)-7 proceeds with very good yields (72 – 100%) together with high syn-selectivities (87 – 97%) and asymmetric inductions (63 – 92%) to give the corresponding α-hydroxyhydrazones 4 and 8. Depending on the substitution patterns of the starting material, opticallyactive aliphatic and aromatic α-hydroxyketones 5 or protected cyanohydrins