Synthesis of trisubstituted alkenes by reductive dehydroxylation of Baylis–Hillman adducts using polymethylhydrosiloxane (PMHS) and catalytic B(C6F5)3
摘要:
B(C6F5)(3) as a catalyst and polymethylhydrosiloxane as a hydride source have been employed for the reductive dehydroxylation of Baylis-Hillman adducts wherein the hydride adds in an S(N)2' manner onto the unactivated allyl alcohol moiety with concomitant elimination of the hydroxy group along with double bond migration. The products formed were found to be E in the case of ester adducts and Z in the case of nitrile adducts. (c) 2006 Elsevier Ltd. All rights reserved.
作者:Ashok K. Basak、Naoyuki Shimada、William F. Bow、David A. Vicic、Marcus A. Tius
DOI:10.1021/ja103028r
日期:2010.6.23
An organocatalytic asymmetric Nazarov cyclization of diketoesters that proceeds by means of a dual activation mechanism has been developed. Screening of a number of catalysts led to a new thiourea that incorporates a primary amino group. The method gives rise to cyclic products with two adjacent quaternaryasymmetriccarbon atoms, one of which is an all-carbon stereocenter, with complete or nearly
An Efficient and General Method for the Heck and Buchwald–Hartwig Coupling Reactions of Aryl Chlorides
作者:Dong-Hwan Lee、Abu Taher、Shahin Hossain、Myung-Jong Jin
DOI:10.1021/ol202177k
日期:2011.10.21
The β-diketiminatophosphane Pd complex acted as a powerful catalyst for the Heck coupling of aryl chlorides with alkenes. Various aryl and heteroaryl chlorides were coupled efficiently under relatively mild conditions. Furthermore, this catalytic system also proved to be highly active in the Buchwald–Hartwig coupling of deactivated and sterically hindered aryl chlorides at room temperature.
Neutral Nazarov-Type Cyclization Catalyzed by Palladium(0)
作者:Naoyuki Shimada、Craig Stewart、William F. Bow、Anais Jolit、Kahoano Wong、Zhe Zhou、Marcus A. Tius
DOI:10.1002/anie.201201724
日期:2012.6.4
Joining the circle: The first Pd0 catalyzed Nazarov‐type cyclization of diketoesters (see scheme) proceeds in 70 % to 95 % yield under strictly neutral pH conditions. Aryl substitution of the diketoesters is not required, so the reaction shows great versatility and can also proceed with aliphatic substrates.
The contra-thermodynamic isomerization of α- and β-substituted cinnamate derivatives catalyzed by the Cu(OAc)2/rac-BINAP complex under blue light irradiation is reported. The use of an oxazolidinone template, which favored the complexation of the copper catalyst to the substrate, allowed the E → Z isomerization of the catalytically formed chromophore under simple and robust reaction conditions in good
Compounds represented by the formula:
1
wherein R
1
and R
2
are hydrogen atom, a hydrocarbon group or a heterocyclic group, or R
1
and R
2
may form, together with the adjacent carbon atom, a 3- to 8-membered homocyclic or heterocyclic ring,
W indicates
(i) a group represented by the formula:
2
wherein ring B indicates a 5- to 7-membered ring, or
(ii) a group represented by the formula:
3
wherein R
4
indicates (1) an aliphatic hydrocarbon group, which may be substituted with an aromatic group, or (2) an acyl group containing an aromatic group, R
5
is hydrogen atom, a C
1-6
alkyl, or an acyl group, provided that, when W is Wa, R
3
is hydrogen atom, a hydrocarbon group or a heterocyclic group, when W is Wb, R
3
indicates a C
6-14
aryl group, or salts thereof or prodrugs thereof have an excellent action to inhibit neurodegeneration and the like as well as an excellent brain penetrability and are low in the toxicity, thereby being useful as prophylactic or therapeutic drugs for nerve degenerative diseases and the like.
由以下公式代表的化合物:
其中 R1 和 R2 是氢原子、烃基或杂环基,或者 R1 和 R2 可以与相邻的碳原子一起形成 3 至 8 个成员的同环或杂环环,W 表示
(i) 由以下公式代表的基团:
其中环 B 表示一个 5 至 7 个成员的环,或者
(ii) 由以下公式代表的基团:
其中 R4 表示 (1) 可以用芳香基取代的脂肪烃基,或者 (2) 含有芳香基的酰基,R5 是氢原子、C1-6 烷基或酰基,提供当 W 是 Wa 时,R3 是氢原子、烃基或杂环基,当 W 是 Wb 时,R3 表示一个 C6-14 芳基,或其盐或前药具有优异的抑制神经退行性等作用,以及出色的脑透过性,毒性低,因此可用作预防或治疗神经退行性疾病等的药物。