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Synfacts mbr+ gati+ mmr+ juillet 2012

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Synfacts mbr+ gati+ mmr+ juillet 2012

  1. 1. Ca t e g o r y W. GATI, M. M. RAMMAH, M. B. RAMMAH, F. COUTY, G. EVANO* (UNIVERSITÉ DE Metal-Mediated Synthesis VE R S A I L L E S S A I N T - Q U E N T I N E N YV E L I N E S , F R A N C E ; U N I V E R S I T É D E M O N A S T I R, Ke y w o rd s TU N I S I A ; U N I V E R S I T É L I B R E D E B R U X E L L E S , B E L G I U M ) De Novo Synthesis of 1,4-Dihydropyridines and Pyridines J. Am. Chem. Soc. 2012, 134, 9078–9081. pyridines 1,4-dihydropyridines N-allyl ynamides Synthesis of 1,4-Dihydropyridines and Pyridines out of N-Allyl Ynamides lithium Boc R1 Boc 1. s-BuLi (1.2 equiv) TMEDA (1.1 equiv) THF, –78 °C, 1 h N R1 2. NH4Cl (sat.) R2 1. s-BuLi (1.2 equiv) TMEDA (1.1 equiv) THF, –78 °C, 1 h N R1 2. o-chloranil (1 equiv) AcOH –78 to 25 °C, 30 min R2 R3 R3 N (1 equiv) quantitative R2 R3 up to 96% yield R = alkyl, (substituted) aryl, styryl R2 = H, Me R3 = H, Me, Ph Selected examples: N N H H t-Bu H Ph H MeO 81% yield N Ph H Ph 81% yield N H Ph 79% yield F 79% yield N t-Bu N H H H 96% yield H 84% yield N H H H 82% yield N Cl N 93% yield Ph H 93% yield Significance: An efficient, general, simple and Comment: The broad availability of the starting modular preparation of 1,4-dihydropyridines and pyridines has been disclosed. The formation of the products proceeds via a lithiation–isomerization– carbolithiation sequence and provides the (dihydro)pyridines in high yields. N-allyl ynamides implies that an extensive range of substituents can be selectively incorporated on the (dihydro)pyridine ring. According to the authors, this is the first example of an anionic 6endo-dig cyclization. SYNFACTS Contributors: Paul Knochel, Christoph Sämann Synfacts 1012, 8(8), 0900 Published online: 19.07.20121861-19581861-194X 2 8 0 DOI: 10.1055/s-0032-1316638; Reg-No.: P09012SF ©oialr Geteo ehV Nue TSk get rw ·gg m Y r a 900 2012 © THIEME STUTTGART • NEW YORK Downloaded by: Harvard University Library. Copyrighted material. 1

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