Convenient Wacker oxidations with substoichiometric cupric acetate
作者:Amos B. Smith、Young Shin Cho、Gregory K. Friestad
DOI:10.1016/s0040-4039(98)01992-3
日期:1998.11
A modification of the Wacker oxidation of terminalolefins to methylketones using substoichiometric amounts of Cu(OAc)2 as a redox shuttle reagent is described. The modified procedure is generally high yielding despite reduced levels of copper salt and convenient. Importantly, in a problematic case, the conditions suppressed acidic hydrolysis during oxidation of substrate (+)-5 containing an acetonide
Claisen Rearrangement Based Methodology for the Spiroannulation of a Cyclopentane Ring. Formal Total Synthesis of (±)-Acorone and Isoacorones
作者:A Srikrishna、P Praveen Kumar
DOI:10.1016/s0040-4020(00)00743-2
日期:2000.10
A Claisen rearrangement based methodology for spiroannulation of a cyclopentane ring to cyclic precursors and its application in the formal total synthesis of acorones 1 is described. Thus, Claisen rearrangement of 2-cycloalkylideneethanols 12 with 2-methoxypropene and a catalytic amount of mercuric acetate generates 4,4-substituted hex-5-en-2-ones 13. Ozonolytic cleavage of the terminal olefin in the enones 13 and intramolecular aldol condensation of the resulting keto-aldehydes 14 furnishes the spiroannulated compounds 15. (C) 2000 Elsevier Science Ltd. All rights reserved.
Oxycyclopropanes in organochemical synthesis. Total syntheses of (.+-.)-.alpha.-cuparenone and (.+-.)-.beta.-vetivone
作者:Ernest Wenkert、Brian L. Buckwalter、Afranio A. Craveiro、Eduardo L. Sanchez、Sharatchandra S. Sathe
DOI:10.1021/ja00472a039
日期:1978.2
Neighboring group participation in Lewis acid-promoted [3 + 4] and [3 + 5] annulations. The stereocontrolled synthesis of tricyclic ethers
作者:Gary A. Molander、Kimberly O. Cameron
DOI:10.1021/jo00074a018
日期:1993.10
A variety of 1,4- and 1,5-keto aldehydes derived from cycloalkanes are coupled with the bis(trimethylsilyl) enol ether of methyl acetoacetate in the presence of either TMSOTf or TrSbCl6 to generate tricyclic ethers. The reactions proceed with excellent regiochemical control by a mechanism involving neighboring group participation. This mechanism involves initial formation of a bicyclic oxocarbenium ion intermediate from the keto aldehyde substrates. The geometries of selected bicyclic intermediates have been optimized using the AM1 method allowing successful prediction of the stereochemical outcomes in the cyclization in most cases. Epimerization of alpha-chiral keto aldehyde substrates does not appear to occur in these Lewis acid-promoted annulation reactions.
COREY E. J.; GHOSH A. K., TETRAHEDRON LETT., 28,(1987) N 2, 175-178