Mo(CO)6 as a Solid CO Source in the Synthesis of Aryl/Heteroaryl Weinreb Amides under Microwave-Enhanced Condition
作者:Raghu Ningegowda、Savitha Bhaskaran、Ayyiliath M. Sajith、Chandrashekar Aswathanarayanappa、M. Syed Ali Padusha、Nanjunda Swamy Shivananju、Babu Shubha Priya
DOI:10.1071/ch16213
日期:——
The facile transformation of aryl/heteroaryl nonaflates into corresponding amides via Pd-catalyzed aminocarbonylation using Mo(CO)6 as a solid CO source under microwave-enhanced condition is reported. The method was found to be tolerant with respect to a diverse range of electronically biased aryl/heteroaryl nonaflates, and exceptional yields were obtained. The optimized protocol was further extended
Synthesis of 3-arylisocoumarins, including thunberginols A and B, unsymmetrical 3,4-disubstituted isocoumarins, and 3-ylidenephthalides via iodolactonization of methyl 2-ynylbenzoates or the corresponding carboxylic acids
carboxylic acids, were used as precursors either to 3-arylisocoumarins, including naturally-occurring thunberginols A and B, or to unsymmetrical 3,4-disubstituted isocoumarins. On the other hand, (Z)- and (E)-3-iodomethylidenephthalides, which were regioselectively prepared by iodolactonization of methyl 2-ethynylbenzoate, were employed as starting materials for the stereospecific synthesis of (Z)- and
5-Iodo-2(2H)-pyranone derivatives have been selectively synthesized by reaction of stereodefined methyl 2-en-4-ynoates with iodine in MeCN, CH2Cl2 or C6H6 at 20degreesC (Method C) or by treatment of these esters with ICl in CH2Cl2 at 20degreesC (Method B). Methods B and C proved also to be suitable for the preparation of 3-aryl-4-iodoisocoumarins from the corresponding methyl 2-(arylethynyl)benzoates. Interestingly, the high selectivity of iodolactonization of stereodefined methyl 2-en-4-ynoates by Method B allowed preparation in moderate yields of 2(2H)-pyranone derivatives by a one-pot sequence of iodolactonization and Stille-type reactions. (C) 2002 Elsevier Science Ltd. All rights reserved.
Palladium-Catalyzed Amination of Aryl Nonaflates
作者:Kevin W. Anderson、Maria Mendez-Perez、Julian Priego、Stephen L. Buchwald
DOI:10.1021/jo034962a
日期:2003.12.1
detailed study of the palladium-catalyzedamination of aryl nonaflates is reported. Use of ligands 2-4 and 6 allows for the catalytic amination of electron-rich and -neutral aryl nonaflates with both primary and secondary amines. With use of Xantphos 5, the catalytic amination of a variety of functionalized aryl nonaflates resulted in excellent yields of anilines; even 2-carboxymethyl aryl nonaflate is effectively
Regioselective Synthesis of Natural and Unnatural (Z)-3-(1-Alkylidene)phthalides and 3-Substituted Isocoumarins Starting from Methyl 2-Hydroxybenzoates
benzene ring, have been selectively and efficiently synthesized by a new protocol which involves: (i) the conversion of methyl 2-hydroxybenzoates into the corresponding nonaflates; (ii) Pd-catalyzed alkynylation reactions of these derivatives; (iii) the conversion of the so obtained methyl 2-(1-alkynyl)benzoates into the corresponding carboxylic acids followed by a transition metal-catalyzed heteroannulation