Two-step allylic carbon insertion between ketone carbonyl and α carbons giving α-quaternary α-vinyl ketones

He, Jing‐Qian; Shibata, Daisuke; Ohno, Chihaya; Okamoto, Sentaro

doi:10.1016/j.tetlet.2008.09.068

Cited by 15 publications

(4 citation statements)

References 51 publications

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“…In this novel method, allyl alcohol A would first be converted into dibromocyclopropane D . The electrocyclic reaction of D would generate carbocation E , which would then undergo a pinacol‐type 1,2‐shift to form carbonyl compound F having a quaternary carbon and a 1‐bromoalkenyl group . Herein, we disclose the first development of a semipinacol rearrangement induced by cleavage of dibromocyclopropane.…”

Section: Methodsmentioning

confidence: 99%

Semipinacol Rearrangement Induced by Cleavage of Dibromocyclopropane

et al. 2020

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A novel semipinacol rearrangement using dibromocyclopropanes as sources of carbocations was developed. Heating dibromocyclopropanes bearing a 1‐hydroxyalkyl group with silver perchlorate and 2,6‐lutidine induced cleavage of the cyclopropane ring to form allyl cations, which underwent 1,2‐shift of a substituent at the α‐position of the hydroxy group to give β,γ‐unsaturated carbonyl compounds having a quaternary carbon at the α‐position. Because the products have convertible functional groups such as bromo, vinyl, and formyl groups, the method is expected to be applicable to the synthesis of various molecules.

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Section: Methodsmentioning

confidence: 99%

Semipinacol Rearrangement Induced by Cleavage of Dibromocyclopropane

et al. 2020

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“…Recently, allenols have been proven as versatile building blocks in organic synthesis 5,[50][51][52][53] . By applying this protocol, acetate-protected trisubstituted a-and b-allenols could be obtained in moderate to good yields (Fig.…”

Section: Resultsmentioning

confidence: 99%

Cadmium iodide-mediated allenylation of terminal alkynes with ketones

et al. 2013

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Allenes are important building blocks in organic synthesis and have attracted much attention from researchers worldwide. So far, mono-and 1,3-disubstituted allenes can be prepared easily by applying the allenylation of terminal alkynes reaction of aldehydes. However, trisubstituted allenes have never been reported using this reaction due to the extremely low reactivity of ketones. Here, we report the one-pot synthesis of trisubstituted allenes from terminal alkynes and ketones utilizing cadmium iodide as the mediator. With this protocol, a series of different allenes, including 1,5-bisallenes and optically active allenols, which are especially important in synthetic chemistry, have been successfully prepared.

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“…Allenes are a class of compounds with two orthogonal π-bonds and have proven to be useful intermediates in organic synthesis. , Of particular interest is 2,3-allenols, which can be used for the synthesis of 2,5-dihydrofurans, 2(5 H )-furanones, vinylic epoxides, β-halo-β,γ-alkenals, , β-halo-β,γ-alkenones, , 2-halo-1,3( Z )-dienes, and allylic alcohols . Thus, it is highly desirable to develop efficient methodologies for the synthesis of optically active 2,3-allenols with high ee value.…”

Section: Synthesis Of the Starting Materialsmentioning

confidence: 99%

An Efficient CuCN-Catalyzed Synthesis of Optically Active 2,3-Allenols from Optically Active 1-Substituted 4-Chloro-2-butyn-1-ols

Kong

et al. 2009

J. Org. Chem.

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The sequential treatment of optically active terminal propargylic alcohols with n-BuLi/(HCHO)(n) and regioselective chlorination afforded the corresponding optically active 4-chloro-2-butyn-1-ols. With R(1) being a methyl or an ethyl group, an alternative for the synthesis of the corresponding optically active propargylic alcohols is the Novozym 435-catalyzed kinetic resolution of these racemic 4-chloro-2-butyn-1-ols. The subsequent reaction of these optically active 4-chloro-2-butyn-1-ols with the corresponding Grignard reagents under the catalysis of 5 mol % of CuCN afforded the optically active secondary 2,3-allenols in good yields with up to >99% ee.

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Two-step allylic carbon insertion between ketone carbonyl and α carbons giving α-quaternary α-vinyl ketones

Abstract: Ketones 1 were converted to α-quaternary α-vinyl ketones 2 by reaction with propargyltitanium reagents, derived from propargyl carbonates 3 and a divalent titanium reagent, followed by rearrangement of the resulting α-allenyl alcohols 4 with NBS.Leave this area blank for abstract info.

Cited by 15 publications

References 51 publications

Semipinacol Rearrangement Induced by Cleavage of Dibromocyclopropane

Semipinacol Rearrangement Induced by Cleavage of Dibromocyclopropane

Cadmium iodide-mediated allenylation of terminal alkynes with ketones

An Efficient CuCN-Catalyzed Synthesis of Optically Active 2,3-Allenols from Optically Active 1-Substituted 4-Chloro-2-butyn-1-ols

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