Total synthesis of (3Z,9Z,6S,7R) and (3Z,9Z,6R,7S)-6,7-epoxy-3,9-octadecadienes

(3Z,9Z,6S,7R)-6,7-epoxy-3,9-octadecadiene (1) and (3Z,9Z,6R,7S)-6,7-epoxy-3,9-octadecadiene (2) have been stereoselectively synthesized in eight steps from 2-pentyn-1-ol with an overall yield of 8%. The key steps involved the Sharpless asymmetric dihydroxylation of (2E)-oct-2-en-5-yn-1-ol (6). The new synthetic method is suitable for multigram-scale preparation of 1 and 2 and might be used for producing sufficient quantities of the sex pheromone components for management of the pest of tea plantations.     

Synthesis of (5R,8S,10R)-6-(Allyloxy)- and (5R,8S,10R)-6-(Propyloxy)ergolines from the 6-Methyl Precursors

Novel (5R,8S,10R)-6-(allyloxy)- and (5R,8S,10R)-6-(propyloxy)ergolines have been synthesized by use of a Meisenheimer [2,3]-sigmatropic rearrangement of a (5R,8S,10R)-6-allyl-ergoline N⁶-oxide as key step.     

Enantiospecific synthesis of (6R,7S,8aR)-dihydroxyindolizidine and (6R,7R,8S,8aR)-trihydroxyindolizidine from D-glucose.

Enantiospecific syntheses of (6R,7S,8aR)-dihydroxyindolizidine (1) and (6R,7R,8S,8aR)-trihydroxyindolizidine (2) from readily available methyl 2-azido-4,6-O-benzylidene-2-deoxy-α-D-altropyranoside (5) are described.     

Total synthesis of (R)- and (S)-turmerone and (7S,9R)-bisacumol by an efficient chemoenzymatic approach

An enantioselective synthesis of (R)-, (S)-turmerone and (7S,9R)-bisacumol is described. The enantiomerically pure key intermediates, a substituted butanoate ester and acid are utilized in the synthesis of both enantiomers of turmerone. The lipase catalyzed resolution studies of the acetate of bisacumol have been exploited towards the total synthesis of the naturally occurring cytotoxic sesquiterpene, (7S,9R)-bisacumol with high diastereoselectivity (94% de).     

Enantiospecific synthesis of polhydroxylated indolizidines related to castanospermine: 1 (6R,7S,8aR)-6,7-dihydroxyindolizidine and (6R,7R,8S,8aR)-6,7,8-trihydroxyindolizidine.

Enantiospecific syntheses of (6R,7S,8aR)-6,7-dihydroxy-indolizidine (3) and (6R,7R,8S,8aR)-6,7,8-trihydroxy-indolizidine (4) from methyl 2-azido-4,6-O-benzylidene-2-deoxy-α-D-altropyranoside (7) are reported. The two synthetic indolizidines (3) and (4) have been tested against a wide range of enzymes.     

Heterotricyclodecane XX (+)-(1S, 3S, 6S, 8S)- und (−)-(1R, 3R, 6R, 8R)-2, 7-Dioxa-twista-4,9-dien

(+)-(1S, 3S, 6S, 8S)- and (?)-(1R, 3R, 6R, 8R)-2,7-dioxa-twista-4,9-diene. A synthesis and the determination of the sense of chirality of (+)-(1S, 3S, 6S, 8S)- and (?)-(1R, 3R, 6R, 8R)-2,7-dioxa-twista-4,9-diene ((+)- 5 and (?)- 5 , respectively) is described.     

Enantioselective synthesis of (6S,7S,9R,10R)-6,9-epoxynonadec-18-ene-7,10-diol,a marine natural product

The title compound has been synthesized in enantiomerically pure form using diethyl L-tartrate as a chiral template.     

Stereoselectivity in Reactions of Metal Complexes IV. Asymmetric Synthesis of (2R, 7S, 10R)- and (2R, 7R, 10R)-2, 10-diamino-5, 5, 7-trimethyl-4, 8-diazaundecanenickel (II) by Stereoselective Hydrogenation of (2R, 10R)-2, 10-diamino-5, 5, 7-trimethyl-4, 8-diaza-7-undecenenickel(II)

The catalytic hydrogenation of (2R, 10R)-2, 10-diamino-5, 5, 7-trimethyl-4, 8-diaza-7-undecenenickel(II) yields two products when the reaction is performed in the presence of ethylenediamine, but only one, when ethylenediamine is absent. The stereochemistry of the reaction is discussed and a proposal for the absolute configuration of the two diastereomeric complexes and the free ligands is given on the base of CD.- and NMR.-spectra.     

Synthesis and modeling study of (2S,5R,6R)- and (2S,5R,6S)-6-hydroxy- 8-(1-decynyl)-benzolactam-V8 as protein kinase C modulators

[structures: see text] Both (2S,5R,6R)- and (2S,5R,6S)-6-hydroxy-8-(1-decynyl)benzolactam-V8 were designed and synthesized as PKC modulators. Biological assays reveal the (6R)-ligand to be 20-fold more potent than its (6S)-counterpart in binding to PKC alpha.     

(1R,2S,5R,8S,9R,10S)-8-甲基-4-氮杂-5-苯基-7-氧杂四环[8.2.1.0~(2,9).0(~4,8)]十三-11-烯-3-酮的合成和晶体结构

为确定内型降冰片烯酰亚胺与甲基格氏试剂反应所得加成产物的结构,合成了标题化合物(C18H19NO2)。其结构通过单晶X-射线衍射分析确定,该晶体属正交晶系,空间群为P212121,a = 6.293(1),b = 14.342(3),c = 16.357(3) 牛琕 = 1476.2(5) ?,Z = 4,Dc = 1.266 g/cm3, (MoKa) = 0.082mm-1,F(000) = 600。晶体结构用直接法解出,最终的偏离因子为R = 0.0535,wR = 0.988。由此晶体结构可确定加成产物为标题化合物,并由1H-NMR数据推测另一加成产物的结构。     

(+)-(1S, 3S, 6S, 8S)-und (−)-(1R, 3R, 6R, 8R)-4, 9-Twistadien: Synthese und Bestimmung der absoluten Konfiguration

(+)-(1S, 3S, 6S, 8S)-and (?)-(1R, 3R, 6R, 8R)-4, 9-Twistadiene: Synthesis and Absolute Configuration A synthesis and the determination of the absolute configuration of (+)-(1S, 3S, 6S, 8S)- and (?)-(1R, 3R, 6R, 8R)-4, 9-twistadiene ((+)- and (?)- 4 , respectively) is described. Their chiroptical properties are compared with those of saturated twistane ((+)- and (?)- 5 ) as well as with those of the unsaturated and saturated 2, 7-dioxatwistane analogs (+)- and (?)- 9 , and (+)- and (?)- 10 , respectively, which also are compounds of known absolute configurations.     

Total synthesis of (4R,5S,6E,14S)- and (4R,5S,6E,14R)-cystothiazoles F

Total synthesis of (4R,5S,6E,14S)- and (4R,5S,6E,14R)-cystothiazoles F 3 was achieved from the chiral bithiazole-type primary alcohols [(S)- and (R)-4-ethoxycarbonyl-2′-(1-hydroxymethylethyl)-2,4′-bithiazoles 8], which were obtained based on the enzymatic resolution of racemic alcohol 8 and its acetate 9. From a direct comparison by means of chiral HPLC between natural cystothiazole F 3 and synthetic compounds [(4R,5S,6E,14S)- and (4R,5S,6E,14R)-cystothiazoles 3], natural cystothiazole F 3 was found to be a 33:67 diastereomeric mixture [(4R,5S,6E,14S)-3:(4R,5S,6E,14R)-3 = 33:67].     

Chemoenzymatic synthesis of (2R,6R,10R)-6,10,14-trimethylpentadecan-2-ol, sex pheromone of rice moth (Corcyra cephalonica), and of its (2S,6R,10R)-diastereomer

Based on the catalyzed by lipase Amano PS kinetic separation of the two-component mixture of diastereomers of (2RS,6R,10R)-6,10,14-trimethylpentadecan-2-ol in the acylation with the succinic anhydride we obtained the (2R,6R,10R)-6,10,14-trimethylpentadecan-2-ol, the sex pheromone of rice moth (Corcyra cephalonica) and its (2S,6R,10R)-diastereomer.     

Synthesis and Conformation of (5R,8R,10R)-8-(Methylthiomethyl)ergoline-6-carboxamidine

The title compound 7 and two related novel ergolines have been synthesised from (5R,8R,10R)-8-(methyl-thiomethyl)ergoline-6-carbonitrile ( 4 ). The guanidine function of 7 induces a boat conformation of ergoline-ring D, as demonstrated by a careful NMR spectroscopic analysis of 7 and its N-hydroxy congener 6 . Diphenylphosphinodithioic acid has been used to convert the cyanamide function of 4 into the thiourea function at (5R,8R,10R)-8-(methylthiomethyl)ergoline-6-thiocarboxamide ( 5 ).     

Heterotricyclodecane VIII. (−)-(1S, 3R, 6R, 8R)-2, 7-Dioxaisotwistan und (−)-(1R, 3R, 6R, 8R)-2, 7-Dioxa-twistan; Synthese und Bestimmung der absoluten Konfiguration

A synthesis and the determination of the absolute configuration of (?)-(1S, 3R′ 6R, 8R)-2, 7-dioxa-isotwistane ( 13 ) and (?)-(1R, 3R, 6R, 8R)-2, 7-dioxa-twistane ( 14 ) is described. The results for 14 are compared with those for carboeyclic (+)-twistane ( 2 ) of known chirality.