58130-11-3Relevant academic research and scientific papers
Stereospecific construction of chiral tertiary and quaternary carbon by nucleophilic cyclopropanation with bis(iodozincio)methane
Nomura, Kenichi,Matsubara, Seijiro
supporting information; experimental part, p. 147 - 152 (2010/04/23)
The reaction of a ketone having a leaving group at the aposition, such as a,bepoxy ketone or asulfonyloxy 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 that has a leaving group. When an optically active a,β-epoxy ketone or asulfonyloxy ketone is treated with the dizinc, a zinc alkoxide of cyclopropanol having a chiral tertiary or quaternary carbon in the cyclopropane ring is obtained, and the obtained zinc alkoxide of cyclopropanol acts as a chiral ho-moenolate. When it is treated with an electrophile in the presence of copper cyanide, it gives an optically active a-tertiary or -quaternary ketone that retains high optical purity.
Preparation of zinc-homoenolate from α-sulfonyloxy ketone and bis(iodozincio)methane
Nomura, Kenichi,Matsubara, Seijiro
, p. 164 - 165 (2007/10/03)
Treatment of α-sulfonyloxy ketone with bis(iodozincio)-methane gives a zinc cyclopropoxide which is formed via a nucleophilic addition of the reagent to carbonyl group followed by an intramolecular substitution reaction. Copyright
Stereoselective synthesis of δ-lactones from 5-oxoalkanals via one-pot sequential acetalization, tishchenko reaction, and lactonization by cooperative catalysis of samarium ion and mercaptan
Hsu,Fang
, p. 8573 - 8584 (2007/10/03)
By the synergistic catalysis of samarium ion and mercaptan, a series of 5-oxoalkanals was converted to (substituted) δ-lactones in efficient and stereoselective manners. This one-pot procedure comprises a sequence of acetalization, Tishchenko reaction and lactonization. The deliberative use of mercaptan, by comparison with alcohol, is advantageous to facilitate the catalytic cycle. The reaction mechanism and stereochemistry are proposed and supported by some experimental evidence. Such samarium ion/mercaptan cocatalyzed reactions show the feature of remote control, which is applicable to the asymmetric synthesis of optically active δ-lactones. This study also demonstrates the synthesis of two insect pheromones, (2S,5R)-2-methylhexanolide and (R)-hexadecanolide, as examples of a new protocol for asymmetric reduction of long-chain aliphatic ketones.
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
Crotti, Paolo,Di Bussolo, Valeria,Favero, Lucilla,Macchia, Franco,Pineschi, Mauro,Napolitano, Elio
, p. 5853 - 5866 (2007/10/03)
The results obtained in the base-catalyzed intramolecular cyclization of enolates derived from 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 app
Conjugate addition of allylic groups to α,β-unsaturated carbonyl compounds via (η3-allyl)Fe(CO)2NO complexes
Itoh, Keiji,Nakanishi, Saburo,Otsuji, Yoshio
, p. 215 - 224 (2007/10/02)
(η3-Allyl)Fe(CO)2NO complexes undergo conjugate addition to α,β-unsaturated carbonyl compounds to give the corresponding δ,ε-unsaturated carbonyl compounds 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-unsaturated carbonyl compounds to give 1,8-dicarbonyl compounds.The mechanisms and reactivity of these conjugate addition reactions are discussed.Key words: Iron; Carbonyl; Allyl; Silicon; Nitrosyl; Ketone
Neighboring group participation in Lewis acid-promoted [3 + 4] and [3 + 5] annulations. The synthesis of oxabicyclo[3.n.1]alkan-3-ones
Molander, Gary A.,Camera, Kimberly O.
, p. 830 - 846 (2007/10/02)
Lewis acids are employed as catalysts in the annulation of 1,4- and 1,5-dicarbonyl dielectrophiles with bis(trimethylsilyl) end ethers of β-diketones and β-keto esters. A variety of 2-(alkoxycarbonyl)-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 regiocontrol is observed, and good to excellent stereochemical control can be achieved at virtually every position on the new carbocycles. Intramolecular neighboring group participation is proposed to explain the unusually high selectivities attained in the annulation reaction.
Preparation and Reactivities of (η3-1- and 2-Trimethylsiloxyallyl)Fe(CO2)NO Complexes. Intermediates Functioning as Equivalents of β- and α-Acyl Carbocations and Acyl Carbanions
Itoh, Keiji,Nakanishi, Saburo,Otsuji, Yoshio
, p. 2965 - 2977 (2007/10/02)
(η3-1- and 2-Trimethylsiloxyallyl)Fe(CO)2NO complexes were prepared by the reaction of the corresponding siloxyallylic halides with Bu4N.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 for both of β-acyl carbocations and β-acyl carbanions and (η3-2-trimethylsiloxyallyl)Fe(CO)2NO complexes as both of α-acyl carbocations and α-acyl carbanions.The stereochemical courses of the reactions are described.
