opening reaction of the enantioenriched propargyl epoxide 16 (derived from a Sharpless epoxidation) with a Grignard reagent. Allenol 17 was then cyclized with the aid of Ag(I) to give dihydrofuran 19 containing the (R)-configured tetrasubstituted sp3 chiral center at C.19, which was further elaborated into tetrahydrofuran 25 representing the common heterocyclic motif of 1 and 2. The aliphatic chain of amphidinolide
描述了细胞毒性海洋天然产物amphidinolide X (1) 和amphidinolide Y (2) 以及非天然类似物19-epi-amphidinolide X (47) 的简明总合成。这些结构上相当不寻常的次级代谢物的高度收敛路线的关键步骤包括通过铁催化的对映体富集的炔丙基环氧化物 16(源自 Sharpless 环氧化)与格氏试剂的开环反应,顺式选择性形成丙二烯醇 17 . 然后在 Ag(I) 的帮助下将 Allenol 17 环化,得到二氢呋喃 19,该二氢呋喃 19 在 C.19 处含有 (R) 构型的四取代 sp3 手性中心,其进一步细化为代表 1 和 2 的常见杂环基序的四氢呋喃 25。 amphidinolide X 的脂肪族链在 C.10 和 C 处具有反构型立体二联体。11 是通过钯催化、Et2Zn 促进的对映纯甲磺酸炔丙酯 29 加成到官能化醛 28 中产生的。
Iodotrifluoromethylation of Alkenes and Alkynes with Sodium Trifluoromethanesulfinate and Iodine Pentoxide
作者:Zhaojia Hang、Zejiang Li、Zhong-Quan Liu
DOI:10.1021/ol501380e
日期:2014.7.18
A scalable, selective, and operationally easy iodotrifluoromethylation of a wide range of alkenes and alkynes by using two simple and safe solids, sodiumtrifluoromethanesulfinate and iodine pentoxide, in aqueous medium has been developed. Mechanistic studies confirm that free-radical processes are involved in this system since the key radical intermediates such as CF3 and β-CF3 alkyl radicals have
electronically unbiased alkenes has been developed, providing straightforward access to secondary aliphatic boronicesters from readily available materials under very mild reaction conditions. The regioselectivity of this reaction is governed by a unique pyridyl carboxamide ligated catalyst, rather than the substrates. Moreover, this transformation shows excellent chemo‐ and regio‐selectivity and remarkably
Highly enantioselective and regioselective catalytic dihydroxylation of homoallylic alcohol derivatives
作者:E.J Corey、Angel Guzman-Perez、Mark C Noe
DOI:10.1016/0040-4039(95)00570-3
日期:1995.5
The catalytic dihydroxylation of p-methoxyphenyl ethers of various homoallylicalcohols proceeds with excellent enantioselectivity and in the case of diolefins with regioselectivity due to the favorable influence of the aryl ether moiety, as predicted from a previously proposed transition-state model.
Free-radical anti-Markovnikov hydroalkylation of unactivated alkenes with simple alkanes
作者:Yunfei Tian、Anbo Ling、Ren Fang、Ren Xiang Tan、Zhong-Quan Liu
DOI:10.1039/c8gc01394b
日期:——
A Cu(II)-mediated radical anti-Markovnikov hydroalkylation of unactivated alkenes with simple alkanes via selective C(sp3)–Hbond cleavage was achieved. This reaction features high site-selectivity diverse functional group tolerance, and scalability.