4-dihydroxy-6-methylbenzoic acid and 3,4,5-trihydroxytoluene, respectively. An effective ligand, 2-(di-tert-butylphosphino)biphenyl, was used in the palladium-catalyzed diaryl ether-forming reaction. Five analogouscompounds of gerfelin were also synthesized for a study of the structure-activity relationship.
Synthesis of 2,3-Dihydropyrrolizines from Weinreb 3-(Pyrrolidin-2-ylidene)propionamides or Weinreb<i>N-</i>Vinylprolinamides
作者:Alfonso González-Ortega、Luis Calvo、M. Carmen Sañudo
DOI:10.1055/s-2002-35220
日期:——
Weinreb 3-(pyrrolidin-2-ylidene)propionamides and Weinreb N-vinylprolinamides were used for the synthesis of 2,3-dihydropyrrolizines. The selective reaction of the carboxamide group with organometallic compounds allowed us to obtain a great variety of carbonyl intermediates, analogous to the Hantzsch and Knorr pyrrole synthesis, which were thermally cyclized.
A Novel and Highly Stereoselective Approach to Aza-Spirocycles. A Short Total Synthesis of 2-<i>epi</i>-(±)-Perhydrohistrionicotoxin and an Unprecedented Decarboxylation of 2-Pyrones
作者:Michael J. McLaughlin、Richard P. Hsung、Kevin P. Cole、Juliet M. Hahn、Jiashi Wang
DOI:10.1021/ol020052o
日期:2002.6.1
[reaction: see text] A novel and highly stereoselectivesynthesis of aza-spirocycles is described. An application of this methodology is illustrated as a short and concise totalsynthesis of 2-epi-(+/-)-perhydrohistrionicotoxin with high diastereomeric control at the aza-spirocenter. An unprecedented decarboxylation of the 2-pyrone ring is observed in this totalsynthesis effort.
Pd-catalysed regioselective C–H functionalisation of 2-pyrones
作者:Michael J. Burns、Robert J. Thatcher、Richard J. K. Taylor、Ian J. S. Fairlamb
DOI:10.1039/c0dt00421a
日期:——
A new synthetic methodology for the catalytic CâH functionalisation of 2-pyrones is described which proceeds regioselectively at the C3 position, mirroring the observed regioselectivity in 6Ï-electrocyclisation/oxidative aromatisation reactions of related compounds. Insight into the reaction mechanism is provided, with support for a neutral palladium(II) pathway. Cationic palladium(II) complexes possessing 2-pyrones are unstable and readily undergo PdIIâP transfer at ambient temperature resulting in phosphonium salt formation (and Pd0Ln species).
A Facile Synthetic Route for the Preparation of 4-Substituted 6-Methyl-2-pyrone Derivatives via Organozinc Reagents
作者:Seung-Hoi Kim、Reuben Rieke
DOI:10.1055/s-0031-1289855
日期:2011.12
A novel synthetic pathway for the preparation of 4-substituted 2-pyrone derivatives has been developed. It consists of two different methods; the first represents the Negishi coupling reaction utilizing easily accessible organozinc reagents. More significantly, the other is a new method utilizing a new organozinc reagent, 4-pyronylzinc bromide, which is easily prepared by highly active zinc under mild