Dehydrogenation of alcohols with allyl carbonates catalyzed by palladium or ruthenium complexes
作者:Ichiro Minami、Jiro Tsuji
DOI:10.1016/s0040-4020(01)81672-0
日期:——
alkyl allyl carbonates with a phosphine-free palladium catalyst in acetonltrile affords ketones or aldehydes in high yields. This new method of oxidation of alcohols via allyl carbonates can be applied to various alcohols except simple primary alcohols. The reaction proceeds under neutral conditions and hence various acid- or base-sensitive functional groups are not affected during the reaction. Ruthenium
A total synthesis of (±)-isocomene and (±) β-isocomene by an intramolecular ene reaction
作者:W. Oppolzer、K. Bättig、T. Hudlicky
DOI:10.1016/0040-4020(81)80001-4
日期:1981.1
sesquiterpenes isocomene 1 and β-isocomene 22 have been synthesized starting from 1,7-octadien-3-one 10 in a stereoselective manner. In the key step 12 → 13 (Scheme 5) the C-7, C-8-bond was formed by an intramolecular thermal enereaction. Further transformations of 13 (Scheme 6) involved successively ring contraction 18 → 19, elimination 21 → 22 and olefin isomerization 22 → 1.
The Total Synthesis of (±)-Isocomene by an Intramolecular Ene Reaction. Preliminary communication
作者:Wolfgang Oppolzer、Kurt Bättig、Tomas Hudlicky
DOI:10.1002/hlca.19790620514
日期:1979.7.17
The racemic sesquiterpene isocomene (1) has been synthesized starting from 1,7-octadien-3-one (2) in a stereoselective manner (Scheme 2). In the key step 4 5 the C(7), C(8)-bond was formed by an intramolecular thermal ene reaction. Further elaboration of 5 involved the ring contraction 6 7, the elimination 8 9 and the final olefin isomerization 9 1.
congested neopentyl ketone in 10 proved to be problematic. Reaction of the enol triflate 1111 with lithium dimethylcuprate led to reduction to the disubstituted alkene without incorporation of the requisite methyl group.12 The desired alkene 12 was ultimately obtained by reaction of 11 with trimethylaluminum under Pd catalysis.13 Successful alkenylation at this sterically hindered position using palladium-mediated
New Methods for the Syntheses of α,β-Unsaturated Ketones, Aldehydes, and Nitriles by the Palladium-Catalyzed Reactions of Allyl β-Oxo Esters, Allyl 1-Alkenyl Carbonates, and Allyl α-Cyano Esters
Allyl β-oxo esters, allyl 1-alkenyl carbonates, and allyl α-cyano esters are converted into α,β-unsaturated ketones, aldehydes, and nitriles by palladium-catalyzed intramolecular decarboxylation-dehydrogenation. Palladium-phosphine complexes such as Pd(OAc)2-PPh3, Pd(OAc)2-dppe, or Pd2(dba)3 - CHCl3-PPh3 are effective catalysts. Yields depend on solvents and on the mole ratio of palladium to phosphine. The optimum Pd/P ratio for each substrate was determined Use of nitriles as solvents is essential for the dehydrogenation.