Total synthesis of grandisine D (5) was achieved by a Brønsted acid mediated Morita−Baylis−Hillman (MBH) ring-closure reaction and stereoselective aldol condensation with (S)-5-methylcyclohexenone (9) as key steps. The MBH approach was also applicable for the construction of the aza-fused bicyclicsystems of pyrrolizidine and stemona alkaloids.
Old Yellow Enzyme-Catalyzed Dehydrogenation of Saturated Ketones
作者:Matthias Schittmayer、Anton Glieder、Michael K. Uhl、Andreas Winkler、Simone Zach、Jörg H. Schrittwieser、Wolfgang Kroutil、Peter Macheroux、Karl Gruber、Spiros Kambourakis、J. David Rozzell、Margit Winkler
DOI:10.1002/adsc.201000862
日期:2011.2.11
isolated, cloned, heterologously expressed and characterized a thermostable oldyellow enzyme (OYE) from Geobacillus kaustophilus. In addition to the expected ‘enone’ reduction, GkOYE also catalyzes the reverse reaction, i.e., the desaturation of CC bonds adjacent to a carbonyl to give the corresponding α,β-unsaturated ketone. The reaction proceeds at the expense of molecular oxygen without the need
Enantioselective Synthesis of
<i>cis</i>
‐Decalin Derivatives by the Inverse‐Electron‐Demand Diels–Alder Reaction of 2‐Pyrones
作者:Xu‐Ge Si、Zhi‐Mao Zhang、Cheng‐Gong Zheng、Zhan‐Ting Li、Quan Cai
DOI:10.1002/anie.202006841
日期:2020.10.12
A novel strategy for the synthesis of cis‐decalins by an ytterbium‐catalyzed asymmetric inverse‐electron‐demand Diels–Alderreaction of 2‐pyrones and silyl cyclohexadienol ethers is reported here. A broad range of synthetically important cis‐decalin derivatives with multiple contiguous stereogenic centers and functionalities are obtained in good yields and stereoselectivities. A full set of diastereomeric
Opticallyactive 2,5-disubstituted-cyclohexen-2-one derivatives have been prepared in a one-pot process consisting of five reaction steps: an organocatalytic asymmetric conjugated addition of beta-ketoesters to alpha,beta-unsaturated aldehydes that proceeds in aqueous solutions or under solvent-free conditions has been implemented in a multi-step process.
Synthesis of Optically Active 5-(<i>tert</i>-Butyldimethylsiloxy)-2-cyclohexenone and Its 6-Substituted Derivatives as Useful Chiral Building Blocks for the Synthesis of Cyclohexane Rings. Syntheses of Carvone, Penienone, and Penihydrone
作者:Georges P-J. Hareau、Masakazu Koiwa、Shinichi Hikichi、Fumie Sato
DOI:10.1021/ja9843122
日期:1999.4.1
Ti(II)-mediated intramolecular nucleophilic acyl substitution reaction and the FeCl3-mediated ring expansion reaction of a 1-hydroxybicyclo[3.1.0]hexane are the key reactions. The enone 1 reacted with higher-order cyanocuprates with excellent diastereoselectivity to afford the trans-addition products, trans-13, in excellent yields. The reaction of 1 with lower-order cyanocuprates proceeded with moderate