The preparation of 1,2,4-triazines from α,β-diketo-ester equivalents and their application in pyridine synthesis
摘要:
The alpha-Chloro-alpha-acetoxy-beta-keto-esters were prepared from beta-keto-esters in good overall yields. These compounds reacted as alpha,beta-diketo-ester equivalents with amidrazones yielding triazines, generally in good yields, or with an amidrazone and 2,5-norbornadiene in a one-pot aza Diels-Alder reaction to give the corresponding pyridines. (c) 2005 Elsevier Ltd. All rights reserved.
A convenient synthesis of substituted 2,2′:6′,2″-terpyridines
作者:Alexander Gehre、Stephen P. Stanforth、Brian Tarbit
DOI:10.1016/j.tetlet.2008.05.128
日期:2008.8
The 2,2′:6′,2″-terpyridines 8a and 8b were prepared in good yield by reacting α-acetoxy-α-chloro-β-keto-esters 1 (R1 = nPr and Ph) with the bis-amidrazone 7 and 2,5-norbornadiene 5 in ethanol at reflux.
A convenient synthesis of pyridine and 2,2′-bipyridine derivatives
作者:Marta Altuna-Urquijo、Alexander Gehre、Stephen P. Stanforth、Brian Tarbit
DOI:10.1016/j.tet.2008.11.090
日期:2009.1
alpha-Chloro-alpha-acetoxy-beta-keto-esters 9 were readily prepared from beta-keto-esters 6 in good overall yields. These compounds reacted as alpha,beta-diketo-ester equivalents 2 with amidrazones 1 yielding triazines 3, generally in good yields. Picolinates 10 provided an alternative source of alpha,beta-diketo-ester equivalents 2 when treated with copper(II) acetate. A 'one-pot' reaction of the alpha,beta-diketo-ester equivalents 2 with amidrazones 1 in the presence of 2,5-norbornadiene 5 in boiling ethanol yielded the pyridines 4 and 2,2'-bipyridines 4 (R-1=2-pyridyl) directly without the need to isolate the corresponding triazines 3. Triazine 3c reacted with the aza-dienophiles 13 and 17 affording the products 16 and 18, respectively, in good yields. (C) 2008 Elsevier Ltd. All rights reserved.