Non-carbonyl-stabilized metallocarbenoids in synthesis: the development of a tandem rhodium-catalyzed bamford-stevens/thermal aliphatic claisen rearrangement sequence.
A tandem rhodium-catalyzed Bamford-Stevens/Claisen rearrangement 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 acid accelerated Claisen rearrangements to provide products of high diastereopurity. Also presented are cascade reactions, wherein a third chemical step occurs after the initial tandem sequence (i.e., Bamford-Stevens/Claisen/ene and Bamford-Stevens/Claisen/Cope).
May
Jeremy A
JA
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
Stoltz
Brian M
BM