Enantiomerically pure α-methoxyaryl acetaldehydes as versatile precursors: a facile chemo-enzymatic methodology for their preparation
摘要:
A facile and efficient synthesis of optically active alpha-methoxyaryl acetic acids (up to 95% ee), alpha-methoxyaryl ethanols (up to 93% ee) and alpha-methoxyaryl acetonitriles (up to 93% ee) was achieved via Arthrobacter sp. lipase-catalyzed kinetic resolution of masked aldehydes as the key synthons, that is, alpha-hydroxyaryl acetaldehyde acetals. (C) 2008 Elsevier Ltd. All rights reserved.
Manganese (II) catalysed Hunsdiecker reaction: A facile entry to α-(dibromomethyl) benzenemethanol
作者:Shantanu Chowdhury、Sujit Roy
DOI:10.1016/0040-4039(96)00343-7
日期:1996.4
Manganese (II) acetate catalysed reactions of α,β - unsaturated aromatic carboxylic acids 1 with NBS (1 and 2 eq.) in MeCN / water afford haloalkenes 2 and α-(dibromomethyl) benzenemethanols 3 respectively.
Catalytic Hunsdiecker Reaction and One-Pot Catalytic Hunsdiecker–Heck Strategy: Synthesis of α,β-Unsaturated Aromatic Halides, α-(Dihalomethyl)benzenemethanols, 5-Aryl-2,4-pentadienoic acids, Dienoates and Dienamides
作者:Dinabandhu Naskar、Sujit Roy
DOI:10.1016/s0040-4020(99)01035-2
日期:2000.3
The reaction of α,β-unsaturated aromatic (or heteroaromatic) carboxylic acids with N-halosuccinimides (1 equiv.) and catalytic tetrabutylammonium trifluoroacetate (0.2 equiv.) in dichloroethane results in facile halodecarboxylation affording the corresponding (E)-halides in good to excellent yields. A similar reaction, but with 2 equiv. of N-halosuccinimides in acetonitrile-water (1:1 v/v) results
α,β-不饱和芳族(或杂芳族)羧酸与N-卤代琥珀酰亚胺(1当量)和催化四丁基三氟乙酸铵(0.2当量)在二氯乙烷中的反应导致容易的卤代羧化,从而得到相应的(E)-卤化物优异的产量。类似的反应,但具有2当量。的N在乙腈-水中(1-1:1 v / v)中的-卤代琥珀酰亚胺导致相应的α-(二卤代甲基)苯甲醇的排他性形成。此外,已开发出一种结合了Hunsdiecker催化反应(在二氯乙烷中使用三氟乙酸四丁基铵)和Heck偶联(使用乙酸钯/三乙胺/三苯基锑/二氯乙烷)的一锅法,用于合成5-芳基-2,4-戊二烯酸,酯和酰胺,产率中等至良好。通过上述途径合成了天然产物胡椒碱和哌瓜胺。机理和理论研究(通过AM1计算)对当前的卤代羧化反应的机理提供了有用的见解,表明离子途径涉及卤离子跨碳-碳双键的攻击,
A fast and selective decarboxylative difunctionalization and cyclization for easy access to gem-dihalo alcohol, ether, ester and bromo-1,4-dioxane
作者:Saikat Khamarui、Deblina Sarkar、Palash Pandit、Dilip K. Maiti
DOI:10.1039/c1cc16126a
日期:——
A general strategy for fast decarboxylative difunctionalization to gem-dihalohydrin, gem-dihaloether, gem-dibromoester and cyclized bromo-1,4-dioxane synthons with outstanding regio- and stereoselectivity is demonstrated.
Enantiomerically pure α-methoxyaryl acetaldehydes as versatile precursors: a facile chemo-enzymatic methodology for their preparation
作者:Buddh Singh、Pankaj Gupta、Asha Chaubey、Rajinder Parshad、Shiromani Sharma、Subhash C. Taneja
DOI:10.1016/j.tetasy.2008.10.023
日期:2008.11
A facile and efficient synthesis of optically active alpha-methoxyaryl acetic acids (up to 95% ee), alpha-methoxyaryl ethanols (up to 93% ee) and alpha-methoxyaryl acetonitriles (up to 93% ee) was achieved via Arthrobacter sp. lipase-catalyzed kinetic resolution of masked aldehydes as the key synthons, that is, alpha-hydroxyaryl acetaldehyde acetals. (C) 2008 Elsevier Ltd. All rights reserved.