Allylic Carbanions Research Articles

アート錯体（ａｔｅ‐ｃｏｍｐｌｅｘ）を用いる高選択的有機合成

The development of several new procedures for highly selective organic synthesis via organic “ate” complexes including lithium, copper, boron, aluminum, and palladium is described. Dialkenylchloroboranes (1) react with 3 molar equivalents of methylcopper to produce symmetrical (E, E) -1, 3-dienes in high yields. It is revealed that the reaction involves the alkenylcopper-boron complex (loose “ate” complex), free alkenylcopper, and/or copper alkenylborate (tight “ate” complex) as the intermediates. These intermediates further react with allylic halides or alkyl halides to produce stereoselectively E-1, 4-dienes or olefins, respectively. New organocopper reagents, such as RCu·BF3 and RCu·BR3, are developed. Complete γ-attack toward allylic halides, direct alkylation of alcohols, and 1, 4-addition to previously unreactive substituted enoate esters and enoic acids are realized by using the former reagent. Stereocontrolled cis-addition to α, β-acetylenic carbonyl derivatives is achieved by using the latter reagent. Regiocontrolled head-to-tail coupling of allylic boron “ate” complexes with allylic halides is accomplished. Complete control to the regiochemistry in the reaction of heteroatom substituted allylic carbanions is realized with the allylic aluminum “ate” complexes which are formed by the addition of triethylaluminum to the carbanions. The stereoselective olefin synthesisvia the reaction of alkenylboranes with palladium acetate is developed.

ChemInform Abstract: NOVEL CARBANION‐INDUCED TYPE OF ENE REACTION

AbstractDas Dien (I) cyclisiert in Gegenwart von n‐Butyllithium/Tetramethylethylendiamin zum Isopropenylcyclopentan (II), das durch Oxidation und anschließende Reduktion mit Natriumborhydrid als Allylalkohol (III) charakterisiert wird.

Novel carbanion-induced type of ene reaction

With BunLi–tetramethylethylenediamine, 3,7-dimethylocta-1,6-diene is cyclised to the allylic carbanion of 1,2-dimethyl-3-isopropenyl cyclopentane.

Syntheses a partir de carbanions allyliques silicies : I. Carbanions derives de monoallylsilanes

Silicon-containing allyl carbanions are obtained from allylsilanes by two procedures. Their reactions with some organic reagents ( ▪, (CH 3) 3SiCl, (Ph) 2CO, RC(O)NMe 2, CO 2 etc.) are studied. They are found useful for the synthesis of various carbon-functional organosilanes.

1,1-Diphenylalkenes. Part V. C-1 vs. C-3 alkylation of allylic carbanions; applicability of the principle of least motion

The product of C-1 alkylation is the only one observed when 1,3,3-triphenylprop-2-enylsodium (1) is alkylated in liquid ammonia. However, exclusive C-3 alkylation results when the 3-phenyl groups are linked by an ortho,-ortho' -bond, as in 2-(fluoren-9-ylidene)-1-phenylethylsodium (2), 2-(fluoren-9-ylidene)ethylsodium (3), or 2-(fluoren-9-ylidene)-1-methylethylsodium (4), or when the 1-phenyl group is reduced, as in 1-cyclohexyl-3,3-diphenylprop-2-enylsodium (5). It is concluded that the principle of least motion is generally applicable to these alkylation reactions and that the reactions of compound (1) are exceptions to the principle.

The influence of solvation of the reactions of an allylic carbanion

Aus dem Phenyl-allyl-sulfid (I) erhalt man die Lithium-Verbindung (II), die anschlie= βend mit Methyljodid, Allylbromid und Aceton bei -20°C und bei -78°C umgesetzt wird.

Synthèse du squalène et d'analogues

The synthesis of squalene and analogues using an allylic carbanion stabilized by sulfur is described. With the same procedure, by addition of one step, highly labelled 3H-squalene is prepared.

Alkylation of allylic carbanions. Directive effects

Alkylation of allylic carbanions. Directive effects