由三氨基吡啶经五,六个步骤制备了两种新型的吡啶基稠合的三杂环(1a,b和2a,b)。一种合成新型吡啶并[3,4- b ]噻吩并[2,3-和3,2- d ]吡咯(1a,b)和吡啶并[4,3- e ]噻吩并[2,3]的合成策略-和3,2- c ]哒嗪(2a,b)已被研究。合适的2-和3- thienoboronic酸(的铃木交叉偶联3,4)和4-溴-3- pyridylpivaloylamide(9),得到二芳基偶联产物(10,11)以高产率(85%)。水解的(2-噻吩基)-偶联产物(12)重氮化和叠氮化物取代,得到3-叠氮基-4-(2-噻吩基)吡啶中间体(72%,14)。通过交换先前的反应顺序来制备3-叠氮基-4-(3-噻吩基)吡啶(15)。所需的β咔啉噻吩类似物(1A,b)通过叠氮基前体(热分解经由氮烯得到的14,15)。通过优化分子内重氮偶联的条件,可以得到相应的哒嗪产物(72–83%,2a,b)。
Preparation of novel pyridine-fused tris-heterocycles; pyrido[4,3-e]pyrrolo-/pyrido[4,3-e]furano[2,3-c]pyridazines and pyrido[3,4-b]pyrrolo[3,2-d]pyrrole
作者:Vegar Stockmann、Kristine L. Eriksen、Anne Fiksdahl
DOI:10.1016/j.tet.2008.09.051
日期:2008.12
Three novel pyrido-fused tris-heterocycles have been prepared based on a Suzuki coupling and subsequent cyclisation approach. Pyrido[4,3-e]pyrrolo[2,3-c]pyridazine (3b, 77%) and pyrido[4,3-e]furano[2,3-c]pyridazine (5b, 76%) were obtained by intramolecular diazocoupling. Successful diazocoupling of furan (5b) is thus reported for the first time by NOBF4 generation of the diazonium intermediate. N-TIPS-pyrido[3
基于铃木偶联和随后的环化方法,已经制备了三种新颖的吡啶基-稠合的三杂环。吡啶[4,3- e ]吡咯并[2,3- c ]哒嗪(3b,77%)和吡啶[4,3- e ]呋喃基[2,3- c ]哒嗪(5b,76%)通过分子内重氮偶联。因此,首次报道了重氮中间体的NOBF 4生成成功地使呋喃(5b)重氮化成功。N -TIPS-吡啶并[3,4- b ]吡咯并[3,2- d ]吡咯(TIPS-4b由于TIPS活化,通过吡啶环氮烯的热环化反应合成了),产率比先前从类似环化反应中获得的产率高得多(71%)。
Formation of new 4-isocyanobut-2-enenitriles by thermal ring cleavage of 3-pyridyl azides
作者:Vegar Stockmann、Jan M. Bakke、Per Bruheim、Anne Fiksdahl
DOI:10.1016/j.tet.2009.02.072
日期:2009.5
A new thermal ring cleavage of 3-pyridyl nitrenes for the formation of 4-isocyanobut-2-enenitrile products is reported. Thermolysis of 4-(thien-3-yl)-3-pyridyl azide 1 and 3-azido-4-(1-TIPS-1H-pyrrol-3-yl)pyridine 5 afforded two new isonitrile-nitrile products by ring cleavage; 4-isocyano-2-(thiophen-3-yl)but-2-enenitrile (3, 27%) and 4-isocyano-2-(1-TIPS-1H-pyrrol-3-yl)but-2-enenitrile (7, 20%), in addition to our previously reported pyrido[3,4-b]thienopyrrole (2, 29%) and pyrido[3,4-b]pyrrolo[3,2-d]pyrrole (6, 71%) products. Minor amounts of 2-(thien-3-yl)-1H-pyrrole-3-carbonitrile (4, 6%), formed by ring contraction, were also isolated after thermolysis of azide 1. Isonitriles 3 and 7 underwent degradation into amine 3b and formamide 7a by acidic hydrolysis. The nature and chemistry of compounds 3, 4 and 7 were investigated. (C) 2009 Elsevier Ltd. All rights reserved.