An efficient synthesis of optically active 4-demethoxy anthracyclinones

Optically active 4-demethoxy-anthracyclinones were synthezised in few steps from lactose as chiral precursor of ring A and from leucoquinizarine as precursor of rings B, C and D.     

An efficient synthesis of optically active 4-demethoxy anthracyclinones

Optically active 4-demethoxy-anthracyclinones related to daunorubicin were synthesized in several steps from lactose as chiral precursor of ring A and from leucoquinizarine as precursor of rings B, C and D.     

A general and highly efficient asymmetric synthesis of optically active anthracyclinones

The title asymmetric synthesis has been developed by featuring bromolactonization of (−)-acetals, derived from 2-acetyl-3,4-dihydronaphthacene-6,11-diones and (2R,3R)-(+)-N,N,N′,N′-tetraalkyltartaric acid diamides, as a key diastereoselective reaction. The produced bromolactone mixtures could be readily converted to the highly optically active key synthetic intermediates of 4-demethoxy- and 11-deoxy-4-demethoxyanthracyclinones.     

Asymmetric total synthesis of optically active α-curcumene

(R)-(?)-α-Curcumene has been prepared in 66% optical yield and in 34% overall yield in five steps by means of asymmetric Grignard cross-coupling reaction catalyzed by a nickel complex of chiral (aminoalkylferrocenyl)phosphine as a key carbon-carbon bond forming step.     

Asymmetric synthesis of optically active tricarbonyliron complexes of 1,3-dienes

Asymmetric coordination of prochiral 1,3-dienes to form optically active (diene)Fe(CO)₃ complexes has been achieved by direct transfer of the Fe(CO)₃ group from chiral enone complexes.     

Asymmetric synthesis of deoxypolypropionate units via stereoselective hydrogenation of optically active cycloheptatriene

Optically active polypropionate units were synthesized in 9-11 steps from 3,5-dimethylphenol. The sequence consists of the Buchner reaction controlled by a chiral 2,4-pentanediol tether and diastereoselective hydrogenation over Raney nickel. [reaction: see text]     

Asymmetric proliferation with optically active polyanilines

Thin optically active polyaniline layers have been shown to function as platforms to induce optical activity in polyanilines (containing achiral dopants) that are formed by subsequent electrodeposition.     

Asymmetric synthesis of new optically active sulfinamides of menthane series and their derivatives

Asymmetric syntheses were performed of neomenthanesulfinamide in the yield of 60% and de 74%, of neomenthanesulfinaldimines and N-substituted neomenthanesulfinamides in 22–80 and 40–90% yields respectively.     

Asymmetric photocycloaddition between furan and optically active ketones

The photochemical reaction between 3β-acetoxyandrost-5-en-17-one4 or (–)-methone5 and furan was preceded by isomerization of the ketones to the corresponding γδ-unsaturated aldehydes which subsequently added to furan furnishing 6-substituted 2,7-dioxabicyclo-[3.2.0]hept-3-enes,8 and9. Under the same conditions 1,2:5,6-di-O-isopropylidene α-d-ribo-hexofuranos-3-ulose12 reacted with furan without any isomerization and afforded all four stereoisomeric bicyclic photoadducts14–17. The ratio of the products resulting from the approach of the furan molecule to12 from the less hindered and from the more hindered sides was 3:1. This pointed at the decisive role of steric factors in controlling the course of photochemical cycloaddition.     

Total synthesis of optically active chanoclavine-I

The total synthesis of optically active chanoclavine-I, an ergot alkaloid, was accomplished using palladium-catalyzed intramolecular cyclization (Heck reaction) as a key step. The conjugate ester (6) was obtained in 2 steps from optically active 4-bromotryptophan (10), and the cyclization of 6 proceeded smoothly without racemization to give the key intermediate, tricyclic tetrahydrobenz[c,d]indole derivative (7), in high yield.     

光学活性姜黄烯化合物的立体选择性合成

本文报道了在手性膦过渡金属配合物催化下,以对溴甲苯与6-甲基-5-庚烯-2-溴化镁(5)经不对称交叉偶联反应合成(R)-(-)-和(S)-(+_)-α-姜黄烯的方法,光学收率分别为44%e.e和50.3%e.e.(R)-(-)-α-姜黄烯经Birch还原得到(R)-(-)-β-姜黄烯.对溴苯甲醚经不对称交叉偶联、Birch还原等反应合成了(S)-(+)-γ-姜黄烯.     

光学活性化合物的工业合成

本文介绍了光学活性化合物研究现状及发展趋势。并从技术和经济角度论述了工业合成光学活性化合物的可能性     

Asymmetric organocatalytic double-conjugate addition of malononitrile to dienones: efficient synthesis of optically active cyclohexanones

9-Amino-9-deoxyepiquinine efficiently catalyzed the double-conjugate addition of malononitrile to dienones. A number of 1,1,2,6-tetrasubstituted cyclohexanones were prepared in good yields, diastereoselectivities, and excellent enantioselectivities.     

Asymmetric synthesis by chiral cobalt catalysts: Homogeneous reduction of ketones to optically active alcohols

The hydrogenation of ketones with Co₂(CO)₆(PR₃)₂ (PR₃ = PPh₂-neomenthyl, PPh₂ -6-deoxo-1,2:3,4-diisopropylidene d-galactose and PMe₂ -menthyl) as catalysts gives optically active alcohols in optical yields of 1.6 to 5%.     

Asymmetric oxidation of prochiral selenides to optically active selenoxides

Oxidation of 1,1-diphenyl-1-methoxy-2-phenylselenylethane and of 1,1-diphenyl-1-methoxy-2-(o-methoxy)phenylselenylethane with the Sharpless reagent afforded the corresponding selenoxides with moderate optical yields.     

Asymmetric polymerization of N-vinylcarbazole with optically active anionic initiators

The anionic polymerization of N-vinylcarbazole(NVC) by using optically active anionic initiators such as the lithium salts of(S)-1-(9H-fluoren-2-yl)-4-isopropyl-4,5-dihydrooxazole((S)-1-FIDH) and(S)-2-(9H-fluoren-2-yl)-4-isopropyl-4,5-dihydrooxazole((S)-2-FIDH) and complexes of(-)-Sparteine with n-butylithium(n-Bu Li-(-)-Sp) or fluorenyl lithium(FILi-(-)-Sp) was achieved. The yield and specific rotation of poly(N-vinylcarbazole)s(poly(NVC)s) were considerably affected by the molar ratio of(S)-FIDH to NVC. The highest yield and specific rotation were obtained with Li-(S)-1-FIDH as an initiator, with a molar ratio of monomer and initiator [M]/[I] = 10/1. The effects of the chiral initiators, type of solvent and the polymerization temperature were investigated. The obtained optical activity of polymers was attributed to asymmetric induction of the chiral initiators.