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1.
Isr J Chem ; 61(5-6): 198-301, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-34334805

RESUMO

Two catalytic systems for the formate-mediated cross-electrophile reductive coupling of 4-iodoansiole with 6-bromopyridines are described. Using homogenous rhodium or heterogeneous palladium catalysts, the product of reductive biaryl cross-coupling could be formed in moderate yield with excellent levels of chemoselectivity.

2.
J Am Chem Soc ; 141(36): 14136-14141, 2019 09 11.
Artigo em Inglês | MEDLINE | ID: mdl-31465211

RESUMO

The first catalytic enantioselective carbonyl (α-amino)allylations are described. Phthalimido-allene 1 and primary alcohols 2a-2z, 2a'-2c' engage in hydrogen auto-transfer-mediated carbonyl reductive coupling by way of (α-amino)allyliridium-aldehyde pairs to form vicinal amino alcohols 3a-3z, 3a'-3c' with high levels of regio-, anti-diastereo-, and enantioselectivity. Reaction progress kinetic analysis and isotopic labeling studies corroborate a catalytic cycle involving turnover-limiting alcohol dehydrogenation followed by rapid allene hydrometalation.


Assuntos
Álcoois/química , Álcoois/síntese química , Alcadienos/química , Hidrogênio/química , Irídio/química , Ftalimidas/química , Catálise , Estrutura Molecular , Oxirredução
3.
Chemistry ; 24(25): 6617-6624, 2018 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-29446504

RESUMO

Exchange of X (F, Cl, OMe) and a substituted enolate chain between SiMe3 and various CuI complexes was examined. Reaction mechanisms pass through a cyclic transition state in which the reaction coordinate is associated with rotation of the SiMe3 moiety. The dependence of the thermodynamic and kinetic features on the nature of the active and ancillary ligands was examined. Formation of copper enolate is shown to be favored when stabilized enolates are used. Replacement of F by Cl reverses the preference of the reaction. This is associated with the small difference between the Cu-Cl and Si-Cl bond energies, in contrast to other Si-X bonds, which are systematically stronger than their Cu-X analogues.

4.
Org Lett ; 20(5): 1444-1447, 2018 03 02.
Artigo em Inglês | MEDLINE | ID: mdl-29437402

RESUMO

The synthesis of cyclic imidazolidines via two N-C bond-forming sequences has been developed. The transformation goes through a (3 + 2)-cycloaddition reaction in the presence of catalytic amounts of palladium by combining several vinyl aziridines and cyclic N-sulfonyl imines. Interestingly, the use of LiCl as additive allowed the improvement of diastereoselectivities when less encumbered substrates were used. The imidazolidine derivatives that bear aminal cores are isolated in high yields (15 examples, up to 96% yield) and diastereoselectivities (up to >20:1).

5.
Chem Soc Rev ; 47(4): 1159-1173, 2018 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-29323678

RESUMO

After seminal Tsuji-Trost reactions (palladium catalyzed allylation of nucleophiles via π-allyl intermediates as electrophiles), the idea of reversal reactivity of π-allyl intermediates (i.e. π-allyl as nucleophiles) has been stated since the eighties. Thanks to different transition metal sources and the modification of their electronic environment through the use of additives and ligands, such 'reactivity switch' of π-allyl intermediates proved its powerfulness allowing high control in regio-, diastereo- and enantio-selectivities. These methodologies have thus emerged as efficient methods in the catalytic enantioselective allylation of carbonyl compounds and imines with a deep impact on natural product and/or drug elaboration. This tutorial review highlights the concept of 'umpoled' reactivity of π-allyl intermediates, relying on selected recent examples.

6.
J Org Chem ; 82(9): 4737-4743, 2017 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-28398050

RESUMO

A straightforward strategy for the syntheses of curcumene and ar-himachalene is reported. Synthetic highlights include a catalytic and asymmetric vinylogous Mukaiyama reaction and a stereospecific hydrogenolysis of a tertiary benzylic center using Pd/C or Ni/Raney catalysts. Notably, using Ni/Raney, the stereoselectivity outcome (inversion vs retention) of the hydrogenolysis depends on the tertiary benzylic alcohol substitution.

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