Carbonyl Allylation in the Absence of Preformed Allyl Metal Reagents: Reverse Prenylation via Iridium-Catalyzed Hydrogenative Coupling of Dimethylallene
摘要:
Iridium-catalyzed hydrogenation of dimethylallene in the presence of aromatic, heteroaromatic, and aliphatic carbonyl electrophiles 1a-12a delivers products of reverse prenylation 1b-12b. Reductive coupling of dimethyl allene to aldehyde 8a under an atmosphere of deuterium provides deuterio -8b. As revealed by H-2 NMR analysis, deuterium incorporation is observed at the vinylic position (80% H-2). Unlike established methods for carbonyl allylation, the present protocol circumvents the use of stoichiometrically preformed organometallic reagents.
Catalytic Carbonyl <i>Z</i>-Dienylation via Multicomponent Reductive Coupling of Acetylene to Aldehydes and α-Ketoesters Mediated by Hydrogen: Carbonyl Insertion into Cationic Rhodacyclopentadienes
作者:Jong Rock Kong、Michael J. Krische
DOI:10.1021/ja0664786
日期:2006.12.1
Exposure of aldehydes or alpha-ketoesters to equal volumes of acetylene and hydrogen gas at ambienttemperature and pressure in the presence of cationic rhodium catalysts provides products of carbonyl Z-butadienylation, which arise via multicomponent coupling of four molecules: two molecules of acetylene, a molecule of vicinal dicarbonyl compound, and a molecule of elemental hydrogen. The collective
[EN] PROCESS FOR DYEING KERATIN FIBRES COMPRISING A DYE/PIGMENT, A PHOTOACTIVE COMPOUND AND A LIGHT SOURCE<br/>[FR] PROCÉDÉ DE TEINTURE DE FIBRES KÉRATINIQUES COMPRENANT UNE TEINTURE/UN PIGMENT, UN COMPOSÉ PHOTOACTIF ET UNE SOURCE LUMINEUSE
申请人:OREAL
公开号:WO2013174871A1
公开(公告)日:2013-11-28
The invention relates to a process for dyeing and/or lightening keratin fibres using i) particular dye(s) and/or pigment(s), ii) photoactive compound(s) and iii) light source(s); a cosmetic composition comprising the ingredients i) and ii); the use of ii) for improving the fastness and/or dyeing and/or lightening of keratin materials in the presence of the ingredients i) and iii) of light source(s), and a multi-compartment device comprising i), ii) and iii). The implementation process and the use i) of particular dye(s) and/or pigment(s) combined with ii) the photoactive compounds and iii) with a light source make it possible especially to obtain lasting coloration on keratin fibres without the use of a reducing agent, and without odour.
An N-protected-3-acetyl-2-azetidinone-4-carboxylic acid ester has the formula:
wherein R1 and R2 are protecting groups.
The compounds are prepared by reacting a Schiff base R2-N=CH-COOR, with diketene in the presence of an imidazole.
In a further step the acetyl group is reduced and the carboxyl protecting group is then removed; the resultant β-lactam compounds are useful as intermediates for the production of carbapenem or penem derivatives.