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
Stoichiometric and catalytic reductive aldol cyclizations of alkynediones induced by Stryker's reagent
作者:Pauline Chiu、Sze Kar Leung
DOI:10.1039/b407842j
日期:——
Conjugate reduction of alkynones by stoichiometric [(Ph3P)CuH]6 or catalytic [(Ph3P)CuH]6 and polymethyl-hydrosiloxane proceeds to cyclization by an aldol reaction with tethered ketones to generate β-hydroxyenones with good diastereoselectivity.
[see reaction]. Conjugate reduction by Stryker's reagent to form copper enolates, followed by intramolecular aldol cyclization, successfully generated five- and six-membered carbocycles in one pot efficiently. This tandem reaction is generally diastereoselective and provides good yields of the beta-hydroxyketones without any dehydration at low temperatures.
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.
Stereoselective formation of carbocycles was carried out through [RhCl(cod)]2-catalyzed reactions of alkenylzirconocene chloride to ω-carbonyl-α,β-ene carbonyls (ketone, ester, and amide) or to bis-enone derivatives. The Rh(I)-catalyzed reaction of alkenylzirconocene chloride with ω-carbonyl-α,β-enoyl amide, which is derived from Oppolzer’s sultam, showed high diastereoselectivity to yield an carbocycle (95%