129887-49-6Relevant academic research and scientific papers
Intramolecular syn and anti hydrosilylation and silicon-assisted cross-coupling: highly regio- and stereoselective synthesis of trisubstituted allylic alcohols.
Denmark, Scott E,Pan, Weitao
, p. 1119 - 1122 (2003)
[reaction: see text] The geometrical isomers of 6-ethylidenedioxadisilacyclohexane were prepared by intramolecular hydrosilylation of an unsymmetrical disiloxane by the use of Pt (syn) and Ru (anti) catalysts. This new class organosilicon reagents underwent cross-coupling reactions with a range of aryl iodides to afford (E)- and (Z)-trisubstituted allylic alcohols in a highly stereospecific fashion.
Stille coupling versus cine substitution. Electronic effects also influence coupling sterically hindered stannanes
Flohr, Alexander
, p. 5177 - 5180 (1998)
Very low ligand to palladium ratios, especially weak ligands and iodides as electrophiles allow Stille couplings to very hindered stannanes, not possible under common conditions. In contrast, the usage of triflates and elevated temperatures yields exclusi
Divergent regioselectivity in the synthesis of trisubstituted allylic alcohols by nickel- and ruthenium-catalyzed alkyne hydrohydroxymethylation with formaldehyde
Bausch, Cory C.,Patman, Ryan L.,Breit, Bernhard,Krische, Michael J.
supporting information; experimental part, p. 5687 - 5690 (2011/08/06)
Stoichiometric metals banned: Nonsymmetrically disubstituted alkynes were converted into primary trisubstituted allylic alcohols upon exposure to paraformaldehyde in the presence of nickel or ruthenium catalysts, which exhibit complementary regioselectivity and complete stereoselectivity in the absence of exogenous reducing agents (see scheme). Copyright
Cuprous chloride accelerated Stille reactions. A general and effective coupling system for sterically congested substrates and for enantioselective synthesis
Han, Xiaojun,Stoltz, Brian M.,Corey
, p. 7600 - 7605 (2007/10/03)
A major limitation of Stille coupling reactions arises from steric screening, especially in the vinylstannane component. For example, with 1- substituted vinylstannanes and aryl perfluoroalkanesulfonates or halides negligible or low yields are generally observed, due to very slow reaction rates and competing cine substitution. This problem has been overcome in the present work through the discovery and application of cuprous chloride as an accelerant for coupling. Thus, using a protocol for coupling that involves the system Pd(PPh3)4/CuCl/LiCl under anaerobic conditions in dimethyl sulfoxide solution at 60 °C, a wide variety of Stille coupling reactions which otherwise fail can be effected in excellent yield (Table 1). The process has been applied to the enantioselective synthesis of the chiral 1- (arylethyl)alkylcarbinol 26, a model for the natural product nicandrenone. The acceleration of Stille coupling by cuprous chloride can be explained by the intervention of a vinylstannane → vinylcopper(I) transmetalation step and a subsequent accelerated coupling of ArPdX with the vinylcopper(I) intermediate.
An antibody-catalyzed allylic sulfoxide-sulfenate rearrangement
Zhou, Zhaohui S.,Flohr, Alexander,Hilvert, Donald
, p. 8334 - 8341 (2007/10/03)
Antibodies SZ-cis-39C11 and SZ-trans-28F8, which were elicited in response to N-aryl-3-methoxy-phenyl proline derivatives, catalyze the [2,3]- sigmatropic rearrangement of allylic sulfoxides to sulfenates. Reduction of the sulfenates with dithiothreitol in situ yields allylic alcohols as the final product. The antibodies achieve rate accelerations in the range 102- 103 over background and exhibit distinctive hapten-dependent substrate specificity and enantio- and diastereoselectivity. Of particular note is the effective chirality transfer from the sulfoxide center to the product alcohol in the SZ-cis-39C11-catalyzed conversion of (Z)-2-(4-methoxyphenyl)-but-2-en- 1-yl 4-nitrophenyl sulfoxide. These properties can be contrasted with those of bovine serum albumin (BSA) which accelerates the same reactions to a comparable extent but does not discriminate between substrate isomers. Partitioning of substrate from aqueous solution into the less polar environment of the protein pocket can account for much of the observed rate enhancement, whereas specific conformational constraints programmed by the haptens must orient the flexible substrate within the induced antibody- combining sites so as to favor certain reaction pathways over others. These studies thus expand the scope of antibody catalysis to an important new class of pericyclic reactions and illustrate how medium effects can be exploited together with conformational constraint to control reactivity and selectivity.
Intramolecular Photocycloaddition of the C=C Double Bond to the CN Triple Bond Resulting in the Formation of a Novel Cyclic System
Sakuragi, Hirochika,Koyama, Toshiya,Sakurazawa, Mamoru,Yasui, Norimichi,Tokumaru, Katsumi,Ueno, Katsuhiko
, p. 1769 - 1772 (2007/10/02)
Irradiation of a bichromophoric 1-(o-cyanobenzyloxy)-2-(p-methoxyphenyl)-2-butene (1a) in cyclohexane gave an isoquinoline derivative, 8-methoxy-6-methyl-11,13-dihydrobenzoxepinoisoquinoline (2a). The structure was determined by X-ray analysis. The formation of 2a can be accounted for by the initial cycloaddition of 1a in the excited singlet state between the C=C double bond and CN triple bond, followed by cleavage of the resulting azetine ring and recyclization.
