Make a macroring in half a day instead of several months.
INTRODUCTION
Macrocycles are not only esthetically pleasing, but they also can contain multiple functional groups. They are, however, difficult to synthesize. For example, preparing sterically crowded, circularly folded aromatic pentamer 1 required a months-long step-by-step process; and it was obtained in an overall yield of only ≈5%
(Qin, B., et al. Org. Lett. 2008, 10, 5127–5130).
The task is much easier now; it can be accomplished in half a day by using a synthetic route developed by H. Zeng and coauthors at the National University of Singapore, Guang Dong University of Technology (China), and Nanyang Technological University (Singapore).
One-pot, multi-molecular macrocyclization allows the highly selective preparation of pentagon-shaped circular aromatic pentamers mediated by an inward-pointing continuous hydrogen-bonding network.
The protocol is based on a hydrogen-bonding–assisted, one-pot macrocyclization reaction. In the presence of coupling reagent POCl3 and organic base Et3N, 3-amino-2-methoxybenzoic acid (2) undergoes self-amidation under mild conditions to give 1 in a high yield (46%) after a 12-h reaction time. The versatility of this highly selective macrocyclization reaction is illustrated by synthesizing derivatives of 2 with various substituents at the 2- and 5-positions. (Chem. Commun. 2011, 47, 5419–5421;
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THANKS AND REGARD'S
DR ANTHONY MELVIN CRASTO Ph.D
DR ANTHONY MELVIN CRASTO Ph.D
MOBILE-+91 9323115463
GLENMARK SCIENTIST , INDIA
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http://anthonycrasto.jimdo.com/
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