共查询到20条相似文献,搜索用时 531 毫秒
1.
从R-(-)-正十三烯-3-醇2所得的R-(+)-醛5与R-(+)亚砜化合物6的不对称醇醛缩合得7a和7b(30∶1).7a经一系列转化得1a.从(5S,6R)-14出发,经两次构型翻转[(5S,6R)-15→(5S,6S)-16和(5S,6S)-17→(5R,6S)-14],得1a的对映体1b.光学活性α-苄氧基醛5与手性亚砜的不对称醇醛缩合,受手性亚砜的1,3-不对称诱导控制,而不是受醛5的1,2-不对称诱导控制. 相似文献
2.
本文报道一个新的可以广泛应用于甾体全合成的光学活性合成原6的合成.从2-乙基-1,3-环戊二酮 8与 γ-羰基亚砜 12b反应所得之对称三酮 9b经啤酒酵母菌不对称还原得到(2R,3S)-(—)-羟基化合物14,从(2R,3S)-(—)-14所得的(2R,3S)-( )-16的甲磺酸酯或对一甲苯磺酸酯用三乙胺消除即得目的物(2R,3S)-( )-6.微生物不对称还原产生的14的绝对构型是把它转变成已知化合物(2R,3S)-( )-17而得到证明的。 相似文献
3.
(+)-1S,2R,5S-8-β萘基薄荷醇的合成 总被引:3,自引:0,他引:3
以R-(+)-Pulegone为起始原料经1,4-加成、溴代、水解、氧化等9步反应合成了手性辅助试剂(+)-1S,2R,5S-8-β-萘基薄荷醇及其差向异构体(一)-1R,2R,5S-8-β-萘基新薄荷醇,总收率分别为24.0%和22.6%. 相似文献
4.
5.
6.
7.
以手性四氢吡咯片段3a和3b为起始原料, 采用汇聚式合成策略, 完成氮杂Solamin类似物(threo-trans-erythro)的两个对应的光学异构体2a(15S,16S, 19S,20R, 34S)和2b(15R,16R,19R,20S, 34S)的不对称合成. 化合物的结构以及四氢吡咯片段的立体构型均通过NMR波谱解析的方法得到确证. 这两个非对映异构体具有相近的体外抗肿瘤活性. 相似文献
8.
2002年初,我们首次发现具有O3NB骨架的手性螺硼酸酯对前手性酮、肟醚、亚胺的不对称硼烷还原及醛的烷基化反应显示出不对称催化活性[1].在前面的论文中,我们报道了此类手性硼化合物催化的前手性酮的不对称硼烷还原反应[2,3],在优选的条件下,(R)-1,1'-联-2-萘酚硼酸-(S)-α,α-二苯基脯氨酯在THF中催化苯乙酮的硼烷还原给出92%对映体过量(R)-仲醇.作为这种研究的继续,在这里我们将报告(R)-或(S)-1,1'-联-2-萘酚硼酸-(S)-脯氨酸酐[(R,S)-1或(S,S)-1]对具C=N键的前手性化合物不对称硼烷还原的催化作用. 相似文献
9.
环己胺与手性元5-(R)-(1′R,2′S,5′R)-孟氧基-3-溴-2(5H)-呋喃酮的不对称M ichael加成/分子内亲核取代反应,得到含有两个新手性中心的氮杂环丙烷/稠合丁内酯标题化合物。对其进行了谱学表征和X-射线单晶衍射测定。标题化合物分子式为C20H33NO3,M r=335.47,三斜晶系,P1空间群,晶胞参数:a=5.438(11)。A,b=8.117(2)。A,c=11.572(2)。A,α=96.84(3)°,β=94.48(3)°,γ=101.86(3),°V=493.5(2)。A3,Z=1,D c=1.129g/cm3,R=0.0867,wR=0.2344。 相似文献
10.
11.
The ring-closing metathesis (RCM) of two types of unsaturated chiral allylamines III, easily available from enantiomerically enriched epoxy alcohols, has been studied. Fully protected allylamines IIIa [(1)R = CH(2)-(CH(2))(n)()-CH=CH(2); (2)R = Boc; (3)R = PMB] have been prepared from unsaturated epoxy alcohols, whereas bis-allylamines IIIb ((1)R = Ph, (2)R = allyl,(3)R = Boc or PMB) have been prepared from 2,3-epoxy-3-phenylpropanol. Both types have been subjected to RCM to provide either cyclic allylamine I or II. The synthetic potential of these intermediates has been demonstrated by the enantioselective synthesis of (2S,3R,4S)-3,4-dihydroxyproline. 相似文献
12.
13.
A convenient approach for the preparation of (2S,3R,4R,5S,6R)-2-(3-(4-ethylbenzyl)-4-chlorophenyl)-6-(hydroxymethyl)- tetrahydro-2H-pyran-3,4,5-triol I is developed. The target compound via four steps is synthesized from 4-bromo-2-(bromomethyl)- 1-chlorobenzene and the isomers of undesired ortho-products were avoided during the preparation. 相似文献
14.
(3R,4aR,5S,6R)-6-Hydroxy-5-methylramulosin (1) was isolated from a culture of a sterile mycelium, which was derived from the green alga, Codium fragile, along with (-)-5-methylmellein (2), (-)-5-hydroxymethylmellein (3), and (-)-(3R,4R)-cis-4-hydroxy-5-methylmellein (4). The absolute configuration of 1 was determined by the NMR data along with the lactone sector rule by circular dichroism (CD). Compound 1 exhibited moderate cytotoxic activity against HeLa cells. 相似文献
15.
A reaction of methyl (4R,5R)-4,5-epoxy-2(E)-hexenoate 1 with N-benzylmethylamine gave a diastereomerically pure methyl (4R,5R)-4,5-epoxy-(3S)-N-benzylmethylamino hexanoate 6 and methyl (4S,5R)-4-N-benzyl-methylamino-5-hydroxy-2(E)-hexenoate 7. The former was chemoenzymatically converted to (-)-osmundalactone 11, which is an aglycone of osmundalin. On the other hand, the directly conjugated addition of dimethylamine to methyl (4S,5S)-4,5-epoxy-2(E)-hexenoate 1 followed by treatment with MeOH at 40 degrees C exclusively provided methyl (4R,5S)-4-dimethylamino-5-hydroxy-2(E)-hexenoate 16, which was converted into L-(-)-forosamine 18. 相似文献
16.
Total syntheses of enantiopure alkaloidal natural products (2S,6R)-dihydropinidine (as hydrochloride) and (2S,6R)-isosolenopsins (as hydrochlorides) were achieved in four steps and in 80-82% total yields by using a synthetic strategy of the formation-cleavage of 1,3-oxazinane. (S)-Betti base was proved to be an excellent chiral auxiliary and a novel Pd/C catalyzed N-debenzylation straightforward to amine hydrochloride was developed in the presence of CH2Cl2. 相似文献
17.
Microbial transformation of 1-menthol (1) by six isolates of soil-borne plant pathogenic fungi Rhizoctonia solani AG-1-IA (Rs24, Joichi-2 and RRG97-1) and AG-1-IB (TR22, R147 and 110.4) as a biocatalyst was investigated. Twenty one days precultivation of Rhizoctonia solani AG-1-IA Rs24 and AG-1-IB 110.4 showed excellent yield (98.5-98.6%) of (-)-(1S,3R,4S,6S)-6-hydroxymenthol (2) and (-)-(1S,3R,4S)-1-hydroxymenthol (3) from 1. 相似文献
18.
Wei ZL Sakamuri S Petukhov PA George C Lewin NE Blumberg PM Kozikowski AP 《Organic letters》2002,4(13):2169-2172
[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. 相似文献
19.
Synthesis and Crystal Structure of 5(R)-(1R,2S,5R)-Menthoxy-4(R)- N-cyclohexylaminobutyrolactone 总被引:1,自引:0,他引:1
1INTRODUCTION Substitutedγ-butyrolactones are a group of impor-tant compounds containing unique carbon skeleton of butyrolactone which is widely present in many natural products and have received considerable interest because of their biological and medicinal properties[1~4].Therefore,much attention has been paid to the new asymmetric methods for synthesi-zing these interesting compounds[5~11].The prece-ding results led us to explore the possibility of using cyclohexylamine to convert5(… 相似文献
20.
Sharutin V. V. Sharutina O. K. Koscheeva L. V. 《Russian Journal of General Chemistry》2021,91(5):840-843
Russian Journal of General Chemistry - Bismuth compounds Ph3Bi[OC(O)R]2 (R = CH2C6H4F-3, C6H3F2-2,3, C6HF4-2,3,4,5) were synthesized by the reaction of triphenylbismuth with a carboxylic acid and... 相似文献