Palladium-catalyzed intramolecular alkyne-carbon monoxide-alkene insertion cascade for synthesis of .alpha.-methylenecyclopentenones
摘要:
A method for the construction of alpha-methylenecyclopentenones fused to five-membered rings using a palladium catalyst is reported. The procedure involves the formation of pi-allylpalladium intermediates that undergo sequential intramolecular alkyne insertion, carbon monoxide insertion, intramolecular alkene insertion, and beta-hydride elimination. Examples of the cyclization are seen in eq 2 and Scheme III.
作者:Juan Marco-Martínez、Verónica López-Carrillo、Elena Buñuel、Raquel Simancas、Diego J. Cárdenas
DOI:10.1021/ja0685598
日期:2007.2.1
Pd-catalyzed cyclization of 1,6-enynes in the presence of bis(pinacolato)diboron affords homoallylic alkylboronates. The reaction is general and proceeds with differently substitutedalkenes and with both internal and terminal alkynes. It tolerates the presence of β-hydrogens and is stereoselective in the formation of both the new stereogenic centers and the alkene. This synthesis of alkylboronates
Catalyst precursors for the catalytic Pauson-Khand reaction
作者:M.E. Krafft、C. Hirosawa、L.V.R. Bonaga
DOI:10.1016/s0040-4039(99)01959-0
日期:1999.12
Dicobalt hexacarbonyl complexes of enynes serve as Co2(CO)8 surrogates for the intramolecular Pauson-Khand cycloaddition. Enynes with polar functional groups allow for easy separation of the catalyst cyclopentenone by-product (acid or base wash, silica gel plug column) from the desired cyclopentenone.
Hexacarbonyldicobalt-alkyne complexes as convenient Co2(CO)8 surrogates in the catalytic Pauson-Khand reaction
作者:David B. Belanger、Tom Livinghouse
DOI:10.1016/s0040-4039(98)01694-3
日期:1998.10
Selected hexacarbonyldicobalt-alkyne complexes have been found to serve as convenient substitutes for the labile Co2(CO)8 in thermal, catalyticPauson-Khandreactions.
Modification and limitations of the Livinghouse catalytic Pauson-Khand reaction
作者:M.E. Krafft、L.V.R. Bonaga、C. Hirosawa
DOI:10.1016/s0040-4039(99)01960-7
日期:1999.12
The difficult and impractical purification of Co2(CO)8 is not necessary in the catalytic thermal Pauson-Khandreaction previously described by Livinghouse.
Thermal promotion of the cobalt catalyzed intramolecular Pauson-Khand reaction — An alternative experimental protocol for cyclopentenone synthesis
作者:David B. Belanger、Donogh J.R. O'Mahony、Tom Livinghouse
DOI:10.1016/s0040-4039(98)01693-1
日期:1998.10
Heat alone has been found sufficient to promote intramolecular Pauson-Khand cyclizations catalyzed by high purity Co-2(CO)(8). The existence of a very narrow thermal window (e.g., 60 degrees C - 70 degrees C) for the attainment of efficient catalysis is a noteworthy characteristic of this process. (C) 1998 Elsevier Science Ltd. All rights reserved.