Palladium(II)-catalyzed dicarboxymethylation of chiral allylic alcohols: chirality transfer affording optically active diesters containing three contiguous chiral centers

Abstract

Pd-catalyzed olefin dicarbonylation of chiral allylic alcohols with chirality transfer affords the chiral alcohol diesters contiguous chiral centers, in good to excellent diastereoselectivities (78-98%).Leave this area blank for abstract info. AbstractThis manuscript describes the extension of Stille's palladium-catalyzed olefin dicarbonylation reaction to chiral allylic alcohols with chirality transfer to afford the corresponding chiral alcohol functionalized with bis-carbomethoxy esters, containing three contiguous chiral centers, in good to excellent diastereoselectivities (78-98%).

Developing asymmetric iron and ruthenium-based cyclone complexes; complex factors influence the asymmetric induction in the transfer hydrogenation of ketones

“…(R)-Alcohol 11b 20 Tethered-TsDPEN (R,R) Ru(II) catalyst 14b (31 mg, 0.005 mmol, 0.5 mol%) was dissolved in anhydrous iPrOH (97 cm 3 ) and warmed to 28 • C. On addition of KOH (in iPrOH, 0.1 M, 2.5 cm 3 , 0.25 mmol) the colourless solution turned dark purple and was stirred at 28 • C for 30 min before TBDMS-3-butyn-2-one 10b (1.840 g, 10 mmol) was added. After 18 h at 28 3315, 2954, 2924, 2887, 2853, 2168, 1470 1358, 1251, 1112, 1072, 1041 and 940 cm -1 ; d H (300 MHz, CDCl 3 ) 4.52 (1H, dq, J 6.6, 5.3, CH(OH)CH 3 ), 1.77 (1H, d, J 5.3, OH), 1.45 (3H, d, J 6.6, CH(OH)CH 3 ), 0.93 (9H, s, SiC(CH 3 ) 3 ), 0.10 (6H, s, Si(CH 3 ) 2 ); d C (100 MHz, CDCl 3 ) 108.35 (quat., C C), 86.64 (quat., C C), 58.75 (CH(OH)CH 3 ), 26.00 (CH 3 ), 24.35 (CH 3 ), 16.42 (quat., SiC(CH 3 ) 3 ), -4.71 (CH 3 , Si(CH 3 ) 2 ). The ee was determined using the acetyl derivative of the alcohol synthesised from reacting a trace amount of the alcohol (<10 mg) with acetic anhydride (<50 mL) and DMAP (<1 mg) in DCM (ca.…”

“…Purification column chromatography (EtOAc/hexane 0% to 1%) afforded a colourless oil (1.121 g, 3.948 mmol, 60%); [a] 28 D +27.3 (c 0.68 in CHCl 3 ); m/z 307.2 [M + 23] + ; (Found (ESI): M + Na 307.1483, C 18 H 24 NaOSi requires 307.1489); n max 2952, 2927, 2884, 2855, 1250 and 1059 cm -1 ; d H (400 MHz, CDCl 3 ) 7.56 (2H, d, J 7.2, Ar), 7.41-7.34 (3H, m, Ar), 5.45 (1H, s, ArCH), 4.41 (1H, dd, 4 J 2.3, J 15.7, OCHH), 4.29 (1H, dd, 4 J 2.3, J 15.7, OCHH), 2.48 (1H, t, 4 J 2.3, C CH), 0.98 (9H, s, SiC(CH 3 ) 3 ), 0.17 (6H, s, Si(CH 3 ) 2 ); d C (100 MHz, CDCl 3 ) 137.65 (ipso, Ar), 128.69 (CH, Ar), 128.44 (CH, Ar), 126.75 (CH, Ar), 102.50 (quat., C C), 91.77 (quat., C C), 74.82 (quat. C C), 70.44 (ArCH), 55.26 (OCH 2 ), 26.05 (SiC(CH 3 ) 3 ), 16.55 (SiC(CH 3 ) 3 ), -4.70 (Si(CH 3 ) 2 ); d Si (99 MHz, CDCl 3 ) -7.51 (s, Si(CH 3 ) 2 C(CH 3 ) 3 ).…”

“…In studies directed at improving the d.e.s of the cyclisation through the use of a larger group on the chiral centre, we examined derivatives of 8 where R 3 = Ph. Ru/TsDPEN catalysts are less effective at reduction of aryl/propargylic ketones 10c-10e, 16 therefore these were reduced using (R)-Alpine borane. 17 For variation of group R 1 , we prepared alcohols (R)-11c-11e however the TMS derivative (R)-11c was prone to loss of the silyl group in the subsequent alcohol alkylation step.…”

“…Ru/TsDPEN catalysts are less effective at reduction of aryl/propargylic ketones 10c-10e, 16 therefore these were reduced using (R)-Alpine borane.…”

Stereochemistry of PdII-Catalyzed THF Ring Formation of ε-Hydroxy Allylic Alcohols and Synthesis of 2,3,5-Trisubstituted and 2,3,4,5-Tetrasubstituted Tetrahydrofurans

“…We have proposed a reaction mechanism (Scheme ) that involves the chiral allylic alcohol-directed formation of the alkene–Pd II –π complex followed by ligand exchange to form another alkene–Pd II –π complex, which then undergoes cis -oxypalladation leading to the alkyl–Pd II –σ complex. Dissociation of the Pd II species furnished the major stereoisomer predominantly.…”