Studies on taxol biosynthesis. Preparation of taxa-4(20),11(12)-dien-5 alpha-acetoxy-10 beta-ol by deoxygenation of a taxadiene tetraacetate obtained from Japanese yew

Taxa-4(20),11(12)-dien-5 alpha-acetoxy-10 beta-ol 6 has been identified as an early stage intermediate involved in the biosynthesis of taxol (Paclitaxel). This compound has been efficiently prepared by Barton deoxygenation of the C-2- and C-14-hydroxyl groups on a derivative semisynthetically prepared from taxa-4(20),11(12)-dien-2 alpha,5 alpha,10 beta-triacetoxy-14 beta-(2-methyl)butyrate (7), a major taxoid metabolite isolated from Japanese yew heart wood. The synthetic methodology is amenable for the preparation of isotopically labeled congeners that will be useful to probe further intermediate steps in the biosynthesis of taxol.     

Uncommon Ozonolysis of 2,3-Seco-24,28-dinorlupa-4(23),20(29)-diene-2,17-dicarbonitrile

Russian Journal of Organic Chemistry - The oxidation of 2,3-seco-24,28-dinorlupa-4(23),20(29)-diene-2,17-dicarbonitrile with ozone in methylene chloride at –40°C afforded a mixture of...     

4－羟基－2，5－二甲基－3（2H）呋喃酮的合成

总结了食品增香剂４－羟基－２．５－二甲基－３（２Ｈ）呋喃国的合成方法，包括近期的合成研究进展，对一些合成方法的优缺点作了评述。参考文献２８篇。     

Combined biotransformations of 4(20),11-taxadienes

Taxuyunnanine C (1) and its analogs (2 and 3), the C-14 oxygenated 4(20), 11-taxadienes from callus cultures of Taxus sp., were regio- and stereo-selectively hydroxylated at the 7β position by a fungus, Abisidia coerulea IFO 4011, and it was interesting that the longer the alkyl chain of the acyloxyl group at C-14 became, the higher the yield of 7β-hydroxylated product was. Besides the three 7β-hydroxylated products (5, 9, 17), other nine new products (7, 11, 12, 14, 15, 16, 18, 20 and 21) and six known products (4, 6, 8, 10, 13 and 19) were obtained. Subsequently, the acetylated derivatives (24 and 27) of 7β-and 9α-hydroxylated products of 1 were regio- and stereo-specifically hydroxylated at the 9α position by Ginkgo cells and 7β position by A. coerulea, respectively. Thus, the two specific oxidations have been combined. These bioconversions would provide not only valuable intermediates for the semi-synthesis of paclitaxel or other bioactive taxoids from 1 and its analogs, but also some useful hints for the biosynthetic pathway of taxoid in the natural Taxus plant.     

Synthesis of 12(S),20-, 12(S),19(R)-, and 12(S),19(S)-dihydroxyeicosa-cis-5,8,14-trans-10-tetraenoic acids,metabolites of 12(S)-hete

Enantiospecific syntheses of the 20- and both 19-hydroxy metabolites of 12(S)-HETE were accomplished using readily available, chiral precursors.     

Inhaltsstoffe des Osmanthus-Absolues. 5. Mitteilung. (8E)-4, 7-Epoxymegastigma-5(11),8-dien

Constituents of Osmanthus absolute, 5th communication. (8 E )-4,7-Epoxymegastigma-5(11),8-diene The title compound 1 has been identified as trace constituent in Osmanthus absolute. The synthesis of 1 was performed by reaction of α-ionone-epoxide ( 4 ) with aluminum tri (isopropylate) in 2-propanol at 130°. Besides 1 we found another bicyclic ether 5 in the lower boiling part of the reaction mixture, and ten further substances with interesting structural features from the less volatile part. Formation mechanism as well as some spectral particularities are discussed in more detail.     

Studies on Heteromacrocyclic Polyether（X） Synthesis and Structural Characterization of 2，3，11，12－Dibenzo－1，4，10，13－tetraselena－7，16－dioxacyclooctadeca－2，11－diene

ＳｔｕｄｉｅｓｏｎＨｅｔｅｒｏｍａｃｒｏｃｙｃｌｉｃＰｏｌｙｅｔｈｅｒ（Ｘ）ＳｙｎｔｈｅｓｉｓａｎｄＳｔｒｕｃｔｕｒａｌＣｈａｒａｃｔｅｒｉｚａｔｉｏｎｏｆ２，３，１１，１２－Ｄｉｂｅｎｚｏ－１，４，１０，１３－ｔｅｔｒａｓｅｌｅｎａ－７，１６－ｄｉ...     

5,12-环氧-1,2,3,4,5,12-六氢-2-并四苯基甲基酮的合成研究

蒽环类抗生素是近年来颇受人们注意的抗肿瘤药物。其配糖体蒽环酮的化学合成也引起了有机化学工作者极大的兴趣。本工作报道了蒽环酮的重要前体——b,12-环氧-1,2,3,4,5,12-六氢-2-并四苯基甲基酮(1)的合成。 1是以2,3,5,6-四甲     

1-[4-(1,2,4-三唑-5-硫酮)]-3-对甲氧基苯甲酰基硫脲镍配合物的晶体结构

采用缓慢蒸发法培养出化合物1-[4-(1,2,4-三唑-5-硫酮)]-3-对甲氧基苯甲酰基硫脲镍配合物晶体,并通过X-射线单晶衍射法测定了晶体结构,它为P2/n空间群的单斜晶体,晶胞参数为α=1.2577(2)nm,b=0.88790(17)nm,c=1.2628(2)nm,V=1.3304(4)nm3,R1=0.0291和wR2=0.0694.     

Cr(CNR)_3Cl_3和Cr(CNR)_3Cl_2B(C_8H_5)_4·H_2O(R=CH_2C_8H_5)的合成和性质研究

长期以来人们对羰基配合物进行了较为充分的研究,但忽略了与之对应的异腈配合物领域。本文在四氢呋喃溶剂中制得两个过渡金属异腈配合物,初步研究了它们的性质,并讨论了它们的红外光谱和热重分析。 1 实验部分 1。1 试剂和仪器 CrCl_3(thf)_3按文献合成。CNCH_2C_6H_5和NaB(C_6H_5)_4购自Aldrich试剂     

2-芳基-5-(2-苯基-4-喹啉基)-1,3,4-恶二唑衍生物的合成及其相关性质的研究

1,3,4-恶二唑衍生物在医药,农药、染料、涂料、高分子合成材料以及有机闪烁体材料等方面有广泛用途。近年来有关合成和生理活性的研究报道甚多。本文选择被淘汰的解热镇痛、去风湿药物