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1.
Angew Chem Int Ed Engl ; 58(10): 3188-3192, 2019 03 04.
Artículo en Inglés | MEDLINE | ID: mdl-30600867

RESUMEN

Herein, we report a catalytic and stereospecific method for the preparation of enantioenriched α-hydroxy cyclopropylboronates with control in four contiguous stereocenters. The reaction involves the borylation of readily available allylic epoxides using an inexpensive Cu(I) salt and a commercially available phosphine ligand. High diastereocontrol is achieved and different diastereomers can be selectively prepared. Functionalization of the carbon-boron bond provides access to different enantiomerically enriched trisubstituted cyclopropanes from a common intermediate.

2.
Chemistry ; 23(69): 17478-17481, 2017 Dec 11.
Artículo en Inglés | MEDLINE | ID: mdl-29083062

RESUMEN

Chiral α-allenols are prepared with high diastereocontrol through an unprecedented and spontaneous ß-oxygen elimination of an α-epoxy vinyl boronate. Stochiometric experiments and DFT calculations support a dual role of the copper catalyst, which orchestrates the hydroboration and the syn-elimination step.

3.
J Am Chem Soc ; 139(30): 10302-10311, 2017 08 02.
Artículo en Inglés | MEDLINE | ID: mdl-28700226

RESUMEN

The intermolecular gold(I)-catalyzed reaction between arylalkynes and alkenes leads to cyclobutenes by a [2 + 2] cycloaddition, which takes place stepwise, first by formation of cyclopropyl gold(I) carbenes, followed by a ring expansion. However, 1,3-butadienes are also formed in the case of ortho-substituted arylalkynes by a metathesis-type process. The corresponding reaction of alkenes with aryl-1,3-butadiynes, ethynylogous to arylalkynes, leads exclusively to cyclobutenes. A comprehensive mechanism for the gold(I)-catalyzed reaction of alkynes with alkenes is proposed on the basis of density functional theory calculations, which shows that the two pathways leading to cyclobutenes or dienes are very close in energy. The key intermediates are cyclopropyl gold(I) carbenes, which have been independently generated by retro-Buchner reaction from stereodefined 1a,7b-dihydro-1H-cyclopropa[a]naphthalenes.

4.
J Am Chem Soc ; 136(45): 15833-6, 2014 Nov 12.
Artículo en Inglés | MEDLINE | ID: mdl-25340304

RESUMEN

A novel Cu-catalyzed diastereo- and enantioselective desymmetrization of cyclopropenes to afford nonracemic cyclopropylboronates is described. Trapping the cyclopropylcopper intermediate with electrophilic amines allows for the synthesis of cyclopropylaminoboronic esters and demonstrates the potential of the approach for the synthesis of functionalized cyclopropanes.


Asunto(s)
Ácidos Borónicos/química , Ácidos Borónicos/síntesis química , Cobre/química , Ciclopropanos/química , Técnicas de Química Sintética , Estereoisomerismo , Temperatura
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