Chromium-Catalyzed Pinacol-Type Cross-Coupling: Studies on Stereoselectivity
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چکیده
منابع مشابه
Chromium-catalyzed pinacol-type cross-coupling: studies on stereoselectivity.
A chromium-catalyzed pinacol-type cross-coupling reaction between alpha,beta-unsaturated carbonyl compounds and aldehydes is reported. Even sterically demanding substrates could be coupled to afford the corresponding pinacols in good yields. Systematic studies concerning the origin of the diastereoselectivities led to the proposal of a mechanism for this synthetically useful reaction. Acroleins...
متن کاملIntramolecular Chromium(II)-Catalyzed Pinacol Cross Coupling of 2-Methylene-α,ω-dicarbonyls
SYNLETT 2004, No. 6, pp 1054–105806.05.2004 Advanced online publication: 25.03.2004 DOI: 10.1055/s-2004-822895; Art ID: G04404ST © Georg Thieme Verlag Stuttgart · New York Abstract: Using only 10% of CrCl2 as catalyst, manganese-powder as reducing agent and TMSCl as scavenger, 2-methylene-a,w-dialdehydes and -ketones can be coupled to form cyclic diols diastereoselectively. The diastereomeric e...
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Synlett 2002, No. 12, Print: 02 12 2002. Art Id.1437-2096,E;2002,0,12,2015,2018,ftx,en;G26802ST.pdf. © Georg Thieme Verlag Stuttgart · New York ISSN 0936-5214 Abstract: Using only 10 mol% of CrCl2 as catalyst, acroleins and , -unsaturated ketones were coupled with aliphatic aldehydes to obtain substituted 1,2-diols using manganese powder as reducing agent and TMS-Cl as scavenger. Diastereoselec...
متن کاملInfluence of chelating silyl scavengers on the diastereoselectivity of chromium catalyzed pinacol cross couplings
The choice of the silyl scavenger shows a substantial influence on the diastereoselectivity of the chromium catalyzed pinacol cross coupling. In the case of the intramolecular cyclization, two competing effects are observed. If the silylation reagents contain chelating heteroatoms in the side chain, a remarkable trans-selectivity is observed. Conversely the cis-diols are preferred if bulky subs...
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Simple iron salts such as FeCl(n), Fe(acac)(n) (n = 2,3) or the salen complex 4 turned out to be highly efficient, cheap, toxicologically benign, and environmentally friendly precatalysts for a host of cross-coupling reactions of alkyl or aryl Grignard reagents, zincates, or organomanganese species with aryl and heteroaryl chlorides, triflates, and even tosylates. An "inorganic Grignard reagent...
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ژورنال
عنوان ژورنال: Chemistry - A European Journal
سال: 2005
ISSN: 0947-6539,1521-3765
DOI: 10.1002/chem.200400304