排序方式: 共有47条查询结果,搜索用时 15 毫秒
1.
An efficient palladium-catalyzed amination of aromatic bromides with hindered N-alkyl-substituted anilines is described, either using the combination of Pd(OAc)(2) and P(t-Bu)(3) or a palladium(I) tri-tert-butylphosphine bromide dimer, [Pd(mu-Br)(t-Bu(3)P)](2), a new, commercially available, and easily handled catalyst. 相似文献
2.
Yugang Liu Mahavir Prashad Oljan Repi
Thomas J. Blacklock 《Journal of heterocyclic chemistry》2003,40(4):713-716
Palladium‐catalyzed amination of 7‐bromo‐4‐methyl‐2,1,3‐benzothiadiazole ( 7 ) with benzophenone imine as an ammonia equivalent is described as a new, safe and practical alternative to nitration for the synthesis of 7‐amino‐4‐methyl‐2,1,3‐benzothiadiazole ( 1 ) in high yield. This methodology was successfully scaled‐up in the pilot plant on 14.0‐kg scale of 7 and was also utilized for the synthesis of 7‐amino‐4,6‐dimethyl‐2,1,3‐ben‐zothiadiazole ( 12 ) by the amination of 7‐bromo‐4,6‐dimethyl‐2,1,3‐benzothiadiazole ( 10 ). 相似文献
3.
A.K. Koul J.M. Bachhawat B. Prashad N.S. Ramegowda A.K. Mathur N.K. Mathur 《Tetrahedron》1973,29(4):625-628
N (o-nitrobenzoyl)amino acids can be coupled with other amino acids using DCC and the resulting product on hydrogenation gives peptides, containing the anthranilyl group as —NH2 end group. N (anthranilyl)amino acids or peptides can also be obtained by reaction of isatoic anhydride on amino acids or peptides. The anthranilyl end group is easily cleaved by metal (Cu+2) catalysed hydrolysis to give α-amino acid peptides and the insoluble copper(II) anthranilate. 相似文献
4.
A selective 2′-O-methylation of N6-cyclohexyladenosine (2) under phase-transfer catalysis conditions and a preferential crystallization of N6-cyclohexyl-2′-O-methyladenosine (1, SDZ WAG 994) from a mixture of by-products is described. A plausible explanation for the selective crystallization of 1 as a hydrate is presented. 相似文献
5.
Liladhar Waykole Mahavir Prashad Stephen Palermo Oljan Repic Thomas J. Blacklock 《合成通讯》2013,43(12):2159-2163
A practical synthesis of 2-(bromomethyl)naphthalene (1), by selective benzylic bromination of 2-methylnaphthalene (2), with bromine in heptane in the presence of lanthanum acetate hydrate is described. 相似文献
6.
7.
The new molybdenum cyanonitrosyl complexes, R2[Mo(NO)(CN)5]·2H2O (R = Ph4P and Bu4N) and [Mo(NO)(CN)3(L-L)]·H2O [L-L = 相似文献
8.
A one-pot direct regioselective iodination of Fischer-Borsche product using periodic acid in PEG-400
Monica H. Ghom Mahavir S. Naykode Vivek T. Humne Pradeep D. Lokhande 《Tetrahedron letters》2019,60(15):1029-1031
A metal-free and greener approach for the one-pot direct iodination and dehydrogenation of dihydrobenzo[a]carbazoles has been developed using periodic acid in polyethylene glycol-400 (PEG-400) under mild condition. This method has been proven to be tolerate to a broad range of functional groups, with good to excellent yields include metal-free inexpensive catalyst, easy work-up, benign reaction condition and high regioselectivity. The solvent has been successfully recycled up to 5 times without any loss of activity in an aqueous medium. 相似文献
9.
Fei Z Wu Q Zhang F Cao Y Liu C Shieh WC Xue S McKenna J Prasad K Prashad M Baeschlin D Namoto K 《The Journal of organic chemistry》2008,73(22):9016-9021
A practical synthetic strategy to a chiral azabicycclooctanyl derivative (1), a potent DPP-4 inhibitor, starting from a commercially available nortropine is described. The stereogenic center of 1 was established employing a modified protocol of Ellman's diastereoselective addition of a benzylic nucleophile to tert-butanesulfinimine. Other key steps include Corey-Chaykovsky reaction, Meinwald rearrangement, and CDMT-promoted amide bond formation involving a sterically hindered amine 2. 相似文献
10.
Edwin B. Villhauer Zhengming Du Kevin Vargas Lech Ciszewski Yansong Lu Michael Girgis Melissa Lin Mahavir Prashad 《Tetrahedron》2009,65(45):9067-1868
A scalable synthetic strategy of a chiral, trisubstituted imidazolidinone (1), a novel cannabinoid-1 antagonist, starting from a commercially available mandelic acid (5) is described. The key step involves a regio- and stereoselective ring-opening of an aziridinium ion by an aniline nucleophile (3). A mechanistic study revealed the insight into rate amplification at a lower temperature for vicinal diamine 12 formation via a aziridinium ion 14. Although most intermediates are not isolable by crystallization due to their intrinsic physical properties (oil or foamy solid), the reported synthesis furnished pure 1 without any chromatography purification throughout the entire synthesis. Employing green chemistry principles, this novel synthesis appears to be highly efficient for the manufacturing of multi-kilogram quantities of an optically-pure active pharmaceutical ingredient. 相似文献