Rhodium-Catalyzed Asymmetric Conjugate Alkynylation/Aldol Cyclization Cascade for the Formation of α-Propargyl-β-hydroxyketones
作者:Ken-Loon Choo、Mark Lautens
DOI:10.1021/acs.orglett.8b00153
日期:2018.3.2
A rhodium-catalyzedconjugatealkynylation/aldol cyclization cascade was developed. Densely functionalized cyclic α-propargyl-β-hydroxyketones were synthesized with simultaneous formation of a C(sp)–C(sp3) bond, a C(sp3)–C(sp3) bond, as well as three new contiguous stereocenters. The transformation was achieved with excellent enantio- and diastereoselectivities using BINAP as the ligand. The synthetic
Syntheses of α,β-Unsaturated Carbonyl Compounds from the Reactions of Monosubstituted Ozonides with Stable Phosphonium Ylides
作者:Yung-Son Hon、Ling Lu、Rong-Chi Chang、Sheng-Wun Lin、Pei-Pei Sun、Chia-Fu Lee
DOI:10.1016/s0040-4020(00)00903-0
日期:2000.11
Ozonides derived from terminal alkenes reacted with 1.3 mol equiv. of stable phosphonium ylides to give (E)-α,β-unsaturated carbonyl compounds in good to excellent yields. No reducing agent is needed in the reaction. However, alkoxyalkyl-substituted ozonides afforded a mixture of (Z)- and (E)-α,β-unsaturated carbonyl compounds under similar condition. The E/Z isomeric ratio is affected by the position
Diastereo- and Enantioselective Catalytic Carbometallative Aldol Cycloreduction: Tandem Conjugate Addition−Aldol Cyclization
作者:David F. Cauble、John D. Gipson、Michael J. Krische
DOI:10.1021/ja0211095
日期:2003.2.1
A catalytic diastereo- and enantioselective method for tandemconjugateaddition-aldol cyclization is described. This methodology enables the formation of five- and six-membered ring products from aromatic and aliphatic mono-enone mono-ketone precursors. Notably, in a single manipulation, three contiguous stereogenic centers are created with high levels of relative and absolute stereocontrol.
Enantioselective Synthesis of Spiro‐oxiranes: An Asymmetric Addition/Aldol/Spirocyclization Domino Cascade
作者:Ken‐Loon Choo、Bijan Mirabi、Karl Z. Demmans、Mark Lautens
DOI:10.1002/anie.202105562
日期:2021.9.20
Enantioenriched spiro-oxiranes bearing three contiguous stereocenters were synthesized using a rhodium-catalyzed asymmetricaddition/aldol/spirocyclization sequence. Starting from a linear substrate, the cascade enabled the formation of a spirocyclic framework in a single step. sp2- and sp-hybridized carbon nucleophiles were found to be competent initiators for this cascade, giving arylated or alkynylated
The reaction of ozonides from mono-substituted alkenes with stabilized phosphorus ylides
作者:Yung-Son Hon、Ling Lu、Shyh-Yuan Li
DOI:10.1039/c39900001627
日期:——
Ozonides derived frommono-substitutedalkenes react with methyl (triphenylphosphoranylidene)acetate or (triphenylphosphoranylidene)acetophenone to form trans-α,β-unsaturated esters or ketones, respectively, in high yields.