Synthesis of medium-ring lactones via tandem methylenation/Claisen rearrangement of cyclic carbonates
作者:Edward A Anderson、James E.P Davidson、Justin R Harrison、Paul T O'Sullivan、Jonathan W Burton、Ian Collins、Andrew B Holmes
DOI:10.1016/s0040-4020(02)00049-2
日期:2002.3
vinyl-substituted 6- and 7-membered cyclic carbonates into 8- and 9-membered medium-ringlactones has been achieved in good yield using dimethyltitanocene in toluene at reflux. The reaction proceeds by initial formation of a ketene acetal which undergoes subsequent in situ Claisen rearrangement to provide the corresponding lactones. The preparation of the cyclic carbonates is carried out under basic conditions
作者:S. Y. Frankie Mak、Neil R. Curtis、Andrew N. Payne、Miles S. Congreve、Andrew J. Wildsmith、Craig L. Francis、John E. Davies、Sofia I. Pascu、Jonathan W. Burton、Andrew B. Holmes
DOI:10.1002/chem.200701567
日期:2008.3.17
An enantioselective synthesis of the halogenated medium-ring ether natural product (+)-obtusenyne is reported which uses the ring expansion of a seven-membered ketene acetal by means of a Claisen rearrangement to construct the core nine-membered oxygen heterocycle. The trans substituents across the ether linkage were established by using a transition-metal-catalyzed intramolecular hydrosilation reaction