19947-22-9Relevant academic research and scientific papers
Short synthesis of chiral 4-substituted (S)-imidazolinium salts bearing sulfonates and their use in γ-selective reactions of allylic halides with grignard reagents
Latham, Christopher M.,Blake, Alexander J.,Lewis, William,Lawrence, Matthew,Woodward, Simon
supporting information; experimental part, p. 699 - 707 (2012/03/11)
A one-pot reaction of Boc-protected amino alcohols and 2-sulfobenzoic anhydride followed by the addition of a wide variety of primary amines has allowed rapid access to diverse libraries of amidosulfonates 1,2-C 6H4(SO3su
Direct copper-free domino conjugate addition-cycloallylation using organozinc reagents
Komanduri, Venukrishnan,Pedraza, Fernando,Krische, Michael J.
supporting information; experimental part, p. 1569 - 1576 (2009/07/30)
The Direct Approach: Enones possessing appendant allylic carbonates react directly with diorganozinc reagents in the presence of zinc diiodide [ZnI 2] to provide 5- and 6-membered ring products of tandem or domino conjugate addition-cycloallylation in good to excellent yield. In a related copper-free transformation, allylic carbonates are found to engage in direct allylic substitution with diorganozinc reagents.
Catalytic enantioselective synthesis of vicinal dialkyl arrays
Van Zijl, Anthoni W.,Szymanski, Wiktor,Lopez, Ferrnando,Minnaard, Adriaan J.,Feringa, Ben L.
supporting information; body text, p. 6994 - 7002 (2009/05/09)
(Chemical Equation Presented) With a consecutive "asymmetric allylic alkylation (AAA)/cross-metathesis (CM)/conjugate addition (CA)" protocol it is possible to synthesize either stereoisomer of compounds containing a vicinal dialkyl array with excellent stereoselectivity. The versatility of this protocol in natural product synthesis is demonstrated in the preparation of the ant pheromones faranal and lasiol.
Highly enantioselective copper-catalyzed allylic alkylation with phosphoramidite ligands
Van Zijl, Anthoni W.,Arnold, Leggy A.,Minnaard, Adriaan J.,Feringa, Ben L.
, p. 413 - 420 (2007/10/03)
New phosphoramidites were applied as chiral ligands in the Cu-catalyzed allylic alkylation with dialkylzinc reagents. A variety of substrates, reagents and chiral ligands were screened, resulting in improved catalytic methodology for allylic bromides in w
Studies of the formation of all-carbon quaternary centres, en route to lyngbyatoxin A. A comparison of phenyl and 7-substituted indole systems.
Tonder, Janne E,Hosseini, Masood,Ahrenst, Alex B,Tanner, David
, p. 1447 - 1455 (2007/10/03)
Copper mediated allylic substitutions and conjugate additions to geranyl, cinnamyl and allylic indole compounds have been investigated with the aim of finding a method for the creation of the all-carbon quaternary centre present in the natural product lyngbyatoxin A. Reaction conditions have been found giving a 68% SN2' selectivity in the copper mediated addition of PhMgBr to geranyl chloride, as well as 99% and 95% SN2' selectivity in the copper catalysed addition of EtMgBr to cinnamyl chloride and acetate, respectively. When the optimised reaction conditions were applied to the corresponding allylic compounds containing a 7-substituted indole moiety, the regioselectivity was reversed giving only the SN2 product. The allylic indole-containing substrates were also found to be unproductive in Pd- or Mo-catalysed SN2'-type substitution reactions. In related studies, copper catalysed conjugate addition of EtMgBr to the tricyclic lactam 6-methyl-pyrrolo[3,2,1-ij]quinolin-4-one gave a maximum of 20% of the 1,4-addition product.
Heterodimerization of Olefins. 1. Hydrovinylation Reactions of Olefins That Are Amenable to Asymmetric Catalysis
RajanBabu,Nomura, Nobuyoshi,Jin, Jian,Nandi, Malay,Park, Haengsoon,Sun, Xiufeng
, p. 8431 - 8446 (2007/10/03)
Through a systematic examination of ligand and counterion effects, new protocols for a nearly quantitative and highly selective codimerization of ethylene and various functionalized vinylarenes have been discovered. In a typical reaction, 4-bromostyrene and ethylene undergo codimerization in the presence of 0.0035 equiv each of [(allyl)NiBr]2, triphenylphosphine, and AgOTf in CH2Cl2 at -56 °C to give 3-(4-bromophenyl) -1-butene in >98% yield and selectivity. Corresponding reactions with [(allyl)PdX]2 are much less efficient and less selective and may require further optimization before a viable system can be identified. Another useful protocol that gives comparable yield and selectivity involves the use of a single-component catalyst prepared from allyl 2-diphenylphosphinobenzoate, Ni(COD)2, and (C6F5)3B. Recognition of a synergistic relationship between a chiral hemilabile ligand (for example, (R)-2-methoxy-2′-diphenylphosphino-1,1′-binaphthyl, MOP) and a highly dissociated counteranion (BARF or SbF6) in an enantioselective version of the Ni-catalyzed reaction raises the prospects of developing a practical route for the synthesis of 3-arylbutenes. Several pharmaceutically relevant compounds, including widely used 2-arylpropionic acids, can be synthesized from these key intermediates. This reaction appears to be quite general. Synthesis of several new 2-diphenylphosphino-1,1-binaphthyl derivatives, prepared to probe the effect of hemilabile coordination on the efficiency and selectivity of the reaction, are also described.
Synthesis and screening of new chiral ligands for the copper-catalysed enantioselective allylic substitution
Ongeri, Sandrine,Piarulli, Umberto,Roux, Maryline,Monti, Chiara,Gennari, Cesare
, p. 3388 - 3399 (2007/10/03)
The synthesis of the new chiral ligands 6ae, 8ae, 9ae, and 11ae starting from the chiral β[(Boc)amino]-sulfonamide 3ae is reported. The β-amino group of 3ae was deprotected and condensed with 3,5-dichlorosalicylaldehyde (4) to yield the known Schiff base 5ae, which was then reduced to the amino compound 6ae (Scheme 3). Alternatively, condensation of the free amino compound with 2-(diphenylphosphanyl)benz-aldehyde (7) afforded the imino ligand 8ae which upon reduction yielded the amino ligand 9ae (Scheme 4). The free amino compound derived from 3ae was also coupled with 2-(diphenylphosphanyl)benzoic acid (10) to give ligand 11ae (Scheme 5). These ligands were tested in the copper-catalysed allylic substitution reaction of cinnamyl (= 3-phenylprop-2-enyl) phosphate 12 with diethylzinc as a nucleophile. Ligands 5ae, 6ae, 8ae, and 11ae gave excellent ratios (100:0) of the SN2′/SN2 products (Scheme 6 and Table 1). Ligand 11ce, identified from the screening of a small library of ligands of general formula 11, promoted the allylic substitution reaction with moderate enantioselectivity (40% for the SN2′ product 13 (Scheme 8 and Table 3)).
Enantioselective copper-catalyzed SN2' substitution with Grignard reagents
Alexakis,Malan,Lea,Benhaim,Fournioux
, p. 927 - 930 (2007/10/03)
Cinnamyl chlorides undergo selective SN2' allylic substitution by Grignard reagents using catalytic amount (1 mol%) of CuCN and 1-2 mol% trivalent phosphorus ligand, in dichloromethane. With chiral phosphorus ligands derived from TADDOL ee's up
Enantioselective copper-catalyzed allylic alkylation with dialkylzincs using phosphoramidite ligands
Malda, Hinke,Van Zijl, Anthoni W.,Arnold, Leggy A.,Feringa, Ben L.
, p. 1169 - 1171 (2007/10/03)
Matrix presented In the presence of a catalytic amount of copper salts, cinnamyl halides undergo a regio- and enantioselective SN2′ alkylation with dialkylzincs using chiral phosphoramidites as ligands. An SN2′:SN2 ratio o
Synthesis and transformations of metallacycles 26. Cp2ZrCl2-catalyzed cycloalumination of substituted allenes with Et3Al
Khafizova,Ibragimov,Gil'fanova,Khalilov,Dzhemilev
, p. 2188 - 2192 (2007/10/03)
Catalytic cycloalumination of 1-alkyl(phenyl)alleres with triethylaluminum (5 mol.% of Cp2ZrCl2 as the catalyst, -20 °C, 4 h, hexane) afforded methylene- and alkyl(benzyl)idene-substituted alumacyclopentanes.
