Chirality Control in Planar Chiral Cobalt Oxazoline Palladacycles

被引：8

作者：

Cassar, Doyle J. ^{[1
]}

Roghzai, Hemin ^{[1
]}

Villemin, Didier ^{[2
]}

Horton, Peter N. ^{[3
]}

Coles, Simon J. ^{[3
]}

Richards, Christopher J. ^{[1
]}

机构：

[1] Univ E Anglia, Sch Chem, Norwich NR4 7TJ, Norfolk, England

[2] ENSICAEN, Labex EMC3, UMR CNRS 6507, Lab Chim Mol & Thioorgan,INC3M,FR 3038, F-14050 Caen, France

[3] Univ Southampton, Sch Chem, EPSRC Natl Crystallog Serv, Southampton SO17 1BJ, Hants, England

来源：

ORGANOMETALLICS | 2015年 / 34卷 / 12期

关键词：

CATALYTIC ASYMMETRIC-SYNTHESIS; DIASTEREOSELECTIVE ORTHO-LITHIATION; AZA-CLAISEN REARRANGEMENT; ALLYLIC ESTERS; DIRECT ARYLATION; DERIVATIVES; LIGANDS; PALLADATION; MECHANISM; HETEROCYCLES;

D O I：

10.1021/acs.organomet.5b00282

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

Palladation of (eta(5)-(S)-2-(4-R-substituted)-oxazolinylcyclopentadienyl)(eta(4)-tetraphenylcyclobutadiene)cobalt-(I) with Pd(OAc)(2) (R = Me, CH2Cy, CH(2)i-Pr, CH2Ph) resulted exclusively in formation of the (S,Sp)-palladacycle with R = CH2Cy (acetic acid solvent) and up to 13:1 selectivity in favor of the (S,Sp)-palladacycle with R = CH(2)i-Pr (CH2Cl2 solvent). In the latter case diastereomeric purity was achieved by recrystallization, and the absolute configuration of the new element of planar chirality was established by X-ray crystallography. These outcomes contrast with the opposite sense of diastereoselectivity observed for the corresponding R = i-Pr-substituted oxazoline, which results in the palladacycle (S,R-p)-COP-OAc (acetic acid solvent), these palladation reactions being under either kinetic (S,S-p) or thermodynamic (S,Rp) control. Following conversion to the chloride-bridged (S,S-p)-palladacycle dimer (R = CH2Cy), this was employed as a catalyst for the rearrangement of allylic trichloroacetimidates (0.25 mol % catalyst loading, up to 80% ee).

引用

页码：2953 / 2961

页数：9

共 46 条

[1] PREPARATION OF (eta(5)-(S)-2-(4-METHYLETHYL)-OXAZOLINYLCYCLOPENTADIENYL)-(eta(4)-TETRAPHENYLCYCLO-BUTADIENE)COBALT (Cobalt, [1,1',1'',1'''-(eta(4)-1,3-cyclobutadiene-1,2,3,4-tetrayl)tetrakis[benzene]][(1,2,3,4,5-eta)-1-[(4S)-4,5-dihydro-4-(1-methylethyl)-2-oxazolyl]-2,4-cyclopentadien-1-yl]) [J].

Anderson, Carolyn E. ;

Overman, Larry E. ;

Richards, Christopher J. ;

Watson, Mary P. ;

White, Nicole .

ORGANIC SYNTHESES, 2007, 84 :139-+

[2]

[Anonymous], 1843, ECCLESIOLOGIST, V3, P2, DOI DOI 10.1175/1520-0442(2003)016

[3]

[Anonymous], 2010, Chiral Ferrocenes in Asymmetric Catalysis

[4]

[Anonymous], CRYSTALCLEAR SM EXP

[5] Electronic Structures of PdII Dimers [J].

Bercaw, John E. ;

Durrell, Alec C. ;

Gray, Harry B. ;

Green, Jennifer C. ;

Hazari, Nilay ;

Labinger, Jay A. ;

Winkler, Jay R. .

INORGANIC CHEMISTRY, 2010, 49 (04) :1801-1810

[6]

BLANCO J, 1993, Z NATURFORSCH B, V48, P906

[7] Palladium(II)-Catalyzed Enantioselective Synthesis of 2-Vinyl Oxygen Heterocycles [J].

Cannon, Jeffrey S. ;

Olson, Angela C. ;

Overman, Larry E. ;

Solomon, Nicole S. .

JOURNAL OF ORGANIC CHEMISTRY, 2012, 77 (04) :1961-1973

[8] Catalytic Asymmetric Synthesis of Chiral Allylic Esters [J].

Cannon, Jeffrey S. ;

Kirsch, Stefan F. ;

Overman, Larry E. .

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2010, 132 (43) :15185-15191

[9] Mechanism of the Cobalt Oxazoline Palladacycle (COP)-Catalyzed Asymmetric Synthesis of Allylic Esters [J].

Cannon, Jeffrey S. ;

Kirsch, Stefan F. ;

Overman, Larry E. ;

Sneddon, Helen F. .

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2010, 132 (43) :15192-15203

[10] Changing and challenging times for service crystallography [J].

Coles, Simon J. ;

Gale, Philip A. .

CHEMICAL SCIENCE, 2012, 3 (03) :683-689

← 1 2 3 4 5 →