Nazarov Reactions Intercepted by (4 + 3) Cycloadditions with Oxygen-Substituted Dienes
作者:François M. LeFort、Vinayak Mishra、Graham D. Dexter、Timothy D. R. Morgan、D. Jean Burnell
DOI:10.1021/acs.joc.5b00914
日期:2015.6.5
The oxyallyl cation intermediate from the Lewisacidmediated Nazarov reaction of an allenyl vinyl ketone was intercepted by acyclic, 2-silyloxy-substituted butadienes by highly regioselective (4 + 3) cycloadditions. Stereoselectivity was often modest, but in some instances steric interactions were responsible for high selectivity. The results are consistent with concerted (4 + 3) cycloadditions. In
Enantioselective Organocatalytic Singly Occupied Molecular Orbital Activation: The Enantioselective α-Enolation of Aldehydes
作者:Hye-Young Jang、Jun-Bae Hong、David W. C. MacMillan
DOI:10.1021/ja0719428
日期:2007.6.6
e products with uniformly high levels of asymmetric induction. Wide latitude in both the aldehyde and enolsilane component is readily accommodated, allowing generic access to a diverse assortment of enantioenriched 1,4-dicarbonyl compounds. This report highlights the potential of SOMO catalysis to enable the development of entirely new classes of asymmetric reactions that have no traditional catalytic
The clerodane ring system: investigating the viability of a direct Diels–Alder approach
作者:Andrew T. Merritt、Rebecca H. Pouwer、David J. Williams、Craig M. Williams、Steven V. Ley
DOI:10.1039/c1ob05422h
日期:——
A direct synthetic approach to the spiro-γ-lactone clerodane ring system has been investigated. This work builds on that of Jung and highlights the inherent difficulties associated with the otherwise obvious Diels–Alderapproach.
Control of the Regio- and Stereoselectivity in Diels-Alder Reactions with Quinone Boronic Acids
作者:María C. Redondo、Marcos Veguillas、María Ribagorda、M. Carmen Carreño
DOI:10.1002/anie.200803428
日期:2009.1.2
The dienophilic reactivity of 2‐methyl‐substituted quinones has been substantially increased by the introduction of a boronicacid substituent, which makes them equivalent to a highly reactive quinone. The Diels–Alderreactions of these quinones are followed by spontaneous and stereoselective protodeboronation to give the trans‐fused adducts. The boron group is a temporal regiocontroller and leads to
Synthetic studies toward the kempane diterpenes. Diels–Alder additions to bicyclic dienes
作者:Chunjian Liu、Guanglin Bao、D. Jean Burnell
DOI:10.1039/b104924k
日期:2001.10.11
Reduction and then alkylation of a tetracyclic adduct with 1,3-dithienium tetrafluoroborate provided compound 56, which has the correct stereochemistry at three key carbons for elaboration to the kempanediterpenes. Exploratory reactions with tricyclic model compounds and with tetracyclic adducts have been used to assess the development of the desired stereochemistry about the decalin moiety. X-Ray structures