Alkylation of enolates: A new approach to dendrons
摘要:
The synthesis of new polyketonic dendrons is described. These compounds are representative of a new connectivity in dendrimers. The alkylation of enolates and easy functional group interconversion reactions provides a versatile and efficient procedure for the synthesis of this kind of dendron. (C) 1998 Elsevier Science Ltd. All rights reserved.
Metal-Free and Redox-Neutral Conversion of Organotrifluoroborates into Radicals Enabled by Visible Light
作者:Wenbo Liu、Peng Liu、Leiyang Lv、Chao-Jun Li
DOI:10.1002/anie.201807181
日期:2018.10.8
through an SH2 process. This strategy is enabled by using water as the solvent, visible light as the energy input, and diacetyl as the promoter in the absence of any metal catalyst or redox reagent, thereby eliminating metal waste. To demonstrate its synthetic utility, an efficient acetylation to prepare valuable aryl (alkyl) methyl ketones is described and applications to construct C−C, C−I, C−Br
将有机硼化合物转化为相应的基团在有机化学中具有广泛的合成应用。为了实现这些转化,需要采用化学计量的各种强氧化剂如Mn(OAc)3,AgNO 3 / K 2 S 2 O 8和Cu(OAc)2,并通过单电子转移机理进行。本文确立了一种独特的策略,可通过S H从有机三氟硼酸盐生成芳基和烷基2过程。在没有任何金属催化剂或氧化还原试剂的情况下,通过使用水作为溶剂,使用可见光作为能量输入,使用二乙酰作为促进剂来启用此策略,从而消除了金属浪费。为了证明其合成用途,描述了一种有效的乙酰化反应以制备有价值的芳基(烷基)甲基酮,并且构造C-C,C-I,C-Br和C-S键的应用也是可行的。实验证据表明,三联体二乙酰是该过程的关键中间体。
Direct C(sp<sup>3</sup>)–H Cross Coupling Enabled by Catalytic Generation of Chlorine Radicals
作者:Benjamin J. Shields、Abigail G. Doyle
DOI:10.1021/jacs.6b08397
日期:2016.10.5
Here we report the development of a C(sp3)-H cross-coupling platform enabled by the catalytic generation of chlorine radicals by nickel and photoredox catalysis. Aryl chlorides serve as both cross-coupling partners and the chlorine radical source for the α-oxy C(sp3)-H arylation of cyclic and acyclic ethers. Mechanistic studies suggest that photolysis of a Ni(III) aryl chloride intermediate, generated
Five diaroylmethanatoboron difluoride derivatives were prepared from aryl methyl ketones via Claisen condensation with aromatic esters and followed by complexation with boron trifluoride etherate. Their structures and spectroscopic properties were studied by elemental analysis, IR, NMR, ESI–MS, UV and fluorescence spectroscopy. The results showed that these boron complexes had strong fluorescent peaks
A cellulose compound film containing a cellulose compound having two or more substituents whose polarizability anisotropies Δα calculated by mathematical formula (1) are different from each other, wherein substitution degrees of the following substituents A and B in the cellulose compound satisfy relationship as defined by mathematical formula (A1), in which the substituent A has the lowest Δα and the substituent B has the highest Δα:
Δ
α
=
α
x
-
α
y
+
α
z
2
Mathematical
formula
(
1
)
wherein, in characteristic values obtained after diagonalization of polarizability tensor, αx is the largest component, αy is the second largest component, and αz is the smallest component;
DS
B
2+
DS
B
3−
DS
B
6≧−0.1 Mathematical formula (A1)
wherein DS
B
2, DS
B
3, and DS
B
6 represent a substitution degree of the substituent B at the 2-, 3-, or 6-position of a β-glucose ring constituting unit of cellulose, respectively; and
an optical compensation film, a polarizing plate, and a liquid crystal display device, using the cellulose compound film.
describe the unexpected 2-fold Csp3–Csp3 bond cleavage suffered by cyclobutanols in the presence of a catalytic amount of Pd(OAc)2 and promoted by the bulky biaryl JohnPhos ligand. Overall, the sequential cleavage of a strained and an unstrained Csp3–Csp3 bond leads to the formal [2 + 2]-retrocyclization products, namely, styrene and acetophenone derivatives. This procedure might enable the use of cyclobutanols