93921-85-8Relevant articles and documents
Development of domino processes by using 7-silylcycloheptatrienes and its analogues
Beniazza, Redouane,Desvergnes, Valerie,Girard, Emeline,Kauffmann, Brice,Berlande, Muriel,Landais, Yannick
, p. 11976 - 11986 (2012)
7-Silyl- and 7-silylmethylcycloheptatrienes were shown to react with acylnitroso reagents at room temperature, through their norcaradiene forms, to generate the corresponding cycloadducts 5 a-b and 6 a-b as single diastereomers. The course of the reaction was dramatically modified by changing the reaction conditions. Using a polar medium, functionalized cyclohexa-1,3-dienes 7 a-b and bicyclic compounds 13 a-b were instead generated, incorporating one or two amino groups. Similar behavior was observed by using other dienophiles, including triazolinedione, but also activated aldehydes and ketones. A tentative mechanism has been proposed to rationalize the formation of both classes of products that relies on a domino process involving four consecutive elementary steps, in this order: 1)a electrocyclic process, 2)a hetero-Diels-Alder reaction, 3)a cyclopropane ring opening, and 4)a hetero-Diels-Alder reaction. Trapping of the cationic intermediate and isolation of the primary cycloadduct provide support for this hypothesis. An enantioselective version of the cascade using cycloheptatriene 4 b and aldehydes and ketones, under copper(II) catalysis was also carried out, leading to cyclohexa-1,3-dienes 21, 28, and 30 with enantioselectivities up to 93 % ee. Finally, elaboration of the intermediates above has been carried out, opening a straightforward access to sugar mimics 42-43 and complex polycyclic systems 36 and 39.
Alkyl halide-free heteroatom alkylation and epoxidation facilitated by a recyclable polymer-supported oxidant for the in-flow preparation of diazo compounds
Nicolle, Simon M.,Hayes, Christopher J.,Moody, Christopher J.
, p. 4576 - 4579 (2015/03/18)
Highly reactive metal carbenes, generated from simple ketones via diazo compounds, including diazoamides and -phosphonates, using a recyclable reagent inflow, are transient but versatile electrophiles for heteroatom alkylation reactions and for epoxide formation. The method produces no organic waste, with the only byproducts being water, KI and nitrogen, without the attendant hazards of isolation of intermediate diazo compounds.
Highly enantioselective sequential hydrogenation of ethyl 2-Oxo-4-arylbut-3-enoate to ethyl 2-hydroxy-4-arylbutyrate
Meng, Qinghua,Zhu, Lufeng,Zhang, Zhaoguo
supporting information; experimental part, p. 7209 - 7212 (2009/05/07)
(Chemical Equation Presented) The hydrogenation of (E)-ethyl 2-oxo-4-arylbut-3-enoate with [NH2Me2]+[{RuCl [(S)-SunPhos]}2(μ-Cl3)] gave ethyl 2-hydroxy-4- arylbutyrate with 94-96% ee. Further investigation has proved that the hydrogenation proceeded via a sequential hydrogenation of C=O and C=C bonds, which is sensitive to the reaction temperature. Hydrolysis of ethyl 2-hydroxy-4-phenylbutyrate (ee 93%) provided the 2-hydroxy-4-phenylbutyric acid with 81% yield at 99% ee after a single recrystallization from 1, 2-dichloroethylene.
