Alkynyllithium Reagents Research Articles

A new, stereoselective approach to C(7)-alkylated estra-1,3,5(10)-triene derivatives

17β-Acetyloxy-3-methoxy-6-(phenylsulfonyl)estra- 1,3,5(10),6-tetraene ( 4) was prepared as a substrate for conjugate addition of organolithium reagents by a three-step sequence starting from 17β-acetyloxy-3-methoxyestra- 1,3,5(10)-trien-6-one ( 2). While methyllithium showed only poor face selectivity, higher alkyllithium species (n-BuLi, t-BuLi) preferred to add to the β-face of 4. 7α-Substituted derivatives, on the other hand, were generated stereoselectively by utilizing alkynyllithium reagents in the addition step. Removal of the phenylsulfonyl group at C(6) from alkylated products was achieved by conventional reductive desulfonylation methods. A short synthesis of the estrogen receptor antagonist 1 exploiting these observations is presented.

Access to unsaturated chiral epoxides. I: Bisallylic chiral epoxides. Application to the synthesis of lepidopteran pheromones.

A strategy useful in Lepidopteran pheromones synthesis is illustrated by the preparation of compound 1 in optically pure form. The key step relies on the opening of chiral epoxyalcohols by alkynyllithium reagents.

ChemInform Abstract: An Efficient Method for the Alkylation of Chiral Triflates with Alkynyllithium Reagents. A Highly Concise Total Synthesis of (+)‐ Panaxacol.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The preparation of α-tetralones from benzocyclobutenones via sequential thermal electrocyclic reactions

1-Alkenylbenzocyclobuten-1-ols, prepared from benzocyclobutenones via the addition of alkenylmagnesium bromides, or the addition of alkynyllithium reagents followed by ( E)-selective reduction of the triple bond, undergo successive thermal 4π and 6π electrocyclic reactions leading to substituted 3,4-dihydro-1(2 H)-naphthalenones.

An efficient method for the alkylation of chiral triflates with alkynyllithium reagents. A highly concise total synthesis of (+)-panaxacol

An efficient method for the alkylation of triflates with alkynyllithium reagents is described and the successful application of the method to the total synthesis of (+)-panaxacol is exemplified.

Synthesis of 4-ylidenebutenolides. A practical route to 2-en-4-ynoic acid intermediates based on conjugate addition of alkynyl-lithium reagents

Conjugate addition of alkynyl-lithium reagents to diethyl ethoxymethylenemalonate, followed by simultaneous saponification and 1,2-elimination of ethanol from the intermediate adducts, viz(18), in the presence of ethanolic potassium hydroxide, provides a useful synthesis of substituted propargylidenemalonic acids (19). Cyclisation of the propargylidenemalonic acids, using known procedures then leads to the corresponding 4-ylidenebutenolides, e.g.(20) and (21)

Addition of alkynyllithium reagents to the sulfur-sulfur bond of (.mu.-dithio)bis(tricarbonyliron): equilibriums between open sulfur-centered and bridged carbon-centered anions

Addition of alkynyllithium reagents to the sulfur-sulfur bond of (.mu.-dithio)bis(tricarbonyliron): equilibriums between open sulfur-centered and bridged carbon-centered anions

Reaction of α-lactams with alkynyl-lithium reagents: a novel synthesis of pyrrolinones

The reaction of α-lactams with alkynyl-lithium reagents affords 2-pyrrolin-4-ones and constitutes a useful synthesis of this class of heterocycles bearing bulky aliphatic substituents.

Alkylation des carbenoides par des nucleophiles. : II. Substitution nucleophile de l'halogene de carbenoides α phosphonates catalysee par le cuivre(I)

The addition of a catalytic amount (12%) of a copper(I) salt to a mixture of an α-lithio-α-chloroalkylphosphonate and an alkyllithium RLi or a Grignard reagent RMgX leads to the formation of a new organometallic reagent in which the R group has replaced the chlorine atom of the carbenoid. This nucleophilic alkylation of carbenoids can be performed with secondary-alkyl Grignard reagents, and with aryllithium, alkenyllithium and alkynyllithium reagents in good yields (60–80%).

Organoboranes : XVIII. Reaction of lithium alkynes with methyl dialkylborinates: The synthesis of B-1-alkynyldialkylboranes

The reaction of alkynyllithium reagents with methyl dialkylborinates in tetrahydrofuran proceeds readily to form lithium methyl alkynyldialkylborinates. ▪ Reaction of this ”rate“ complex with 1.3 equivalent of boron trifluoride diethyl etherate gives the alkynyldialkylboranes in essentially quantitative yield. ▪