Regio- and stereoselectivity in the cyclization of enolates derived from 4,5-, 5,6-, and 6,7-epoxy-1-phenyl-1-alkanones. Competition between C- and O-alkylation
作者:Paolo Crotti、Valeria Di Bussolo、Lucilla Favero、Franco Macchia、Mauro Pineschi、Elio Napolitano
DOI:10.1016/s0040-4020(99)00226-4
日期:1999.4
The results obtained in the base-catalyzed intramolecular cyclization of enolates derivedfrom some representative 4,5-, 5,6-, and 6,7-epoxy ketones and of the corresponding alkenes are discussed. The LHMDS/Sc(OTf)3 protocol on epoxy ketones appears to be a valuable tool for the stereoselective obtainment of the corresponding cyclic γ-hydroxy ketones (γ-HKs).
Preparation and Reactivities of (η<sup>3</sup>-1- and 2-Trimethylsiloxyallyl)Fe(CO)<sub>2</sub>NO Complexes. Intermediates Functioning as Equivalents of β- and α-Acyl Carbocations and Acyl Carbanions
作者:Keiji Itoh、Saburo Nakanishi、Yoshio Otsuji
DOI:10.1246/bcsj.64.2965
日期:1991.10
(η3-1- and 2-Trimethylsiloxyallyl)Fe(CO)2NO complexes were prepared by the reaction of the corresponding siloxyallylic halides with Bu4N[Fe(CO)3NO]. These complexes reacted with both of carbon nucleophiles and carbon electrophiles preferentially at the less hindered sites of the allylic ligands. In these reactions, (η3-1-trimethylsiloxyallyl)Fe(CO)2NO complexes served as synthetically equivalent synthons
Neighboring group participation in Lewis acid-promoted [3 + 4] and [3 + 5] annulations. The synthesis of oxabicyclo[3.n.1]alkan-3-ones
作者:Gary A. Molander、Kimberly O. Cameron
DOI:10.1021/ja00056a002
日期:1993.2
2-(alkoxycarbon)-m-oxabicyclo[3.n.1]alkan-3-ones can be constructed by this process in which two new carbon-carbon bonds are generated. Unusually high regioncontrol is observed, and good to excellent stereochemicalcontrol can be achieved at virtually every position on the new carbocycles. Intramolecular neighboringgroupparticipation is proposed to explain the unusually high selectivities attained in the annulation
Stereospecific Construction of Chiral Tertiary and Quaternary Carbon by Nucleophilic Cyclopropanation with Bis(iodozincio)methane
作者:Kenichi Nomura、Seijiro Matsubara
DOI:10.1002/asia.200900289
日期:2010.1.4
The reaction of a ketone having a leaving group at the α‐position, such as α,β‐epoxy ketone or α‐sulfonyloxy ketone, with bis(iodozincio)methane affords a zinc alkoxide of cyclopropanol. The reaction proceeds by nucleophilic addition of the dizinc to the carbonyl group and a sequential intramolecular nucleophilic substitution of the introduced iodozinciomethyl group to the adjacent electrophilic carbon
Conjugate addition of allylic groups to α,β-unsaturated carbonyl compounds via (η3-allyl)Fe(CO)2NO complexes
作者:Keiji Itoh、Saburo Nakanishi、Yoshio Otsuji
DOI:10.1016/0022-328x(94)80122-3
日期:1994.6
complexes undergo conjugateaddition to α,β-unsaturatedcarbonylcompounds to give the corresponding δ,ϵ-unsaturated carbonylcompounds in good yields. The reaction of (η3-1-or 2-trimethylsiloxyallyl) Fe(CO)2NO complexes with α,β-unsaturated ketones affords 1,6- or 1,5-diketones, respectively. (η3-1-Acetonylallyl)Fe(CO)2NO complexes also react with α,β-unsaturatedcarbonylcompounds to give 1,8-dicarbonyl