共查询到20条相似文献,搜索用时 66 毫秒
1.
光学活性甾体CD环合成原1a和2a可分别从3a和3b制得.我们已从γ-羰基亚砜5合成了光学活性合成原4.本文报道从一个新的成环试剂7b与2-乙基-环戊烷-1,3-二酮反应得到的三酮硫醚8a来合成2b和4. 二噻烷6a经羟乙基化(n-BuLi,CH_2CH_2O,THF)、水解(HgCl_2-CaCO_3,80% CH_3CN- 相似文献
2.
介绍了“碳中心”手性有机硅化合物的合成,以及在烯丙基硅烷与醛的Hosomi-Sakurai反应和α-烯丙基硅碳负离子与醛的反应中的应用。提出并实践了两条提高对映选择性的途径。烯基硅醇的不对称环氧化反应扩展了Sharpless反应的适用范围,为合成光活性的具简单结构的环氧化合物提供了一条简易的途径。 相似文献
3.
Corey化学酶与不对称合成 总被引:1,自引:0,他引:1
本文从立体化学和反应机理方面综述了Corey化学酶的催化作用及其在有机不对称合成中的应用, 指出了Corey化学酶与酶的相同点和不同点, 对于关键的反应过程态均以空间关系更为清楚的构象式表示。 相似文献
4.
研究了钕、钐、铕、铽、镥的乙酰丙酮化合物,铈、钕、钐、铕、铽、镝、钬、镥的水合氯化物及8-羟基喹啉化合物对环戊二烯与丙烯醛反应的立体化学影响,并比较了在均相反应和异相反应中这些稀土化合物对双烯合成产物的立体选择性的影响。 相似文献
5.
6.
在SmI3作用下和中性室温的条件下, 环戊酮能与醛缩合, 得到几乎定量产率的α, α'-二亚苄基环戊酮; 但对环己酮, 产率仅在20%左右。 相似文献
7.
8.
奈必洛尔的不对称合成 总被引:1,自引:0,他引:1
首先合成4-氟-2-(5-羟基戊烷基-3-烯)-苯酚(2), 再经Sharpless不对称环氧化等反应分别得到2-氨基-1-[6-氟- (2S)-3,4-二氢-2H-2-苯并吡喃]-(1R)-1-乙醇(6)和6-氟-2-[(2R)-2-环氧乙烷基]-(2R)-3,4-二氢苯并吡喃(10). 最后, 6和10发生亲核开环反应即得到目标产物奈比洛尔. 整个合成路线简单易行, 并在原有文献的基础上有较大改进, 使收率大大提高, 总收率由文献的2.1%提高到14.1%. 相似文献
9.
11.
BinSUN LiZengPENG XueSongCHEN YuLinLI YingLI 《中国化学快报》2004,15(10):1177-1178
(-)-(5R, 6S)-6-Acetoxyhexadecan-5-olide 1, a natural mosquito attractant pheromone,was synthesized from readily available aldehyde 2 and cyclopentanone 3 using L-proline-catalyzed asymmetric aldol reaction as the key step. 相似文献
12.
13.
A simple and efficient composite catalyst of L-proline–polyethyleneglycol(PEG)–SiO2 was developed for the asymmetric aldol reaction between acetone and p-nitrobenzaldehyde. With 10 mol% L-proline, the composite catalyst showed much better yield and enantioselectivity than the pristine L-proline over 1.5 h. Clear effects of the molecular weight of PEG and the properties of silica supports on the yield and enantioselectivity were observed, and the optimized catalyst can be reused for four cycles with stable performance. 相似文献
14.
《化学:亚洲杂志》2017,12(1):41-44
This is the first report of a successful asymmetric aldol reaction of acetone and 4‐nitrobenzaldehyde catalyzed by only 0.01 mol % of proline tetrazole (5‐pyrrolidin‐2‐yltetrazole). Amazingly, 3 mol % of water as an additive has significantly improved the efficiency of the aldol reaction in terms of yield and enantioselectivity, up to a 0.1‐mol‐scale production (up to 99 % isolated yield, 84 % ee ). 相似文献
15.
16.
17.
18.
The reactivity of 5-methyl-4-(pyrrolidin-1-yl)-5H-furan-2-one with aldehydes and with acyl chlorides followed by reduction was studied. The aldol condensation gave predominantly the anti aldol product when the acylation-reduction sequence led exclusively to the syn product. The use of a chiral pyrrolidine, (S)-2-methoxymethylpyrrolidine (SMP), allowed the synthesis of enantio-enriched compounds, the acylation-reduction leading to the (R,R) addition product. 相似文献
19.
A formal synthesis of (±)-mitsugashiwalactone ( 1 ) and (±)-isodihydro nepetalactone ( 2 ) was accomplished. Baeyer-Villiger lactonization of ketone 9 followed by acidic treatment led to the rearranged lactone 8 , which underwent a series of functional group transformations to give cyclopentanone derivatives 19 and 20 . Shapiro reaction on 21 and 22 in the presence of excess dry ice gave lactones 5 and 6 . Lactones 5 and 6 previously have been converted to mitsugashiwalactone ( 1 ) and isodihydronepetalactone ( 2 ), respectively. 相似文献
20.
Zhuliang Zhong Donghui Ma Gaoyuan Zhao Huilin Li Dengyu Xu Dr. Xingang Xie Prof. Dr. Xuegong She 《化学:亚洲杂志》2015,10(12):2599-2603
The first asymmetric total synthesis of kravanhin B has been accomplished with a linear reaction sequence of 13 steps starting from (R)‐(?)‐carvone. The synthesis features an intramolecular aldol cyclization to construct the desired cis‐fused decalin skeleton and an acid‐catalyzed dehydration and olefin isomerization to install the γ‐butenolide ring. 相似文献