碳二亚胺9a在138℃下在γ-萜品烯中的热解产生2-(苯氨基)喹啉(11a,49%)和母体6H-吲哚并[2,3-b]喹啉(14a,16%)。显然,通过双自由基10a生成11a,然后从γ-萜品烯中提取氢原子。通过12a的两步双自由基途径或一个分子内Diels-Alder反应一步可提供13a,然后将其进行互变异构化得到14a。对于在乙炔基末端具有三甲基甲硅烷基取代基的碳二亚胺9b,在138℃下在回流的对二甲苯中热解仅产生6H-吲哚并[2,3-b]喹啉14b(86%)。在回流的乙醇中用6 N NaOH处理14b,然后以92%的收率得到14a。类似地,通过碳二亚胺9c-f的热解获得6H-吲哚并[2,3-b]喹啉14c-f。通过使用4-甲氧基苯基异氰酸酯与亚氨基膦酸酯2d和2f之间的氮杂-维蒂希反应来产生相应的碳二亚胺,然后进行热分解,得到在C上具有甲氧基取代基的6H-吲哚并[2,3-b]喹啉16d和16f。
Stereoselective Synthesis of 3-Alkylideneoxindoles by Palladium-Catalyzed Cyclization Reaction of 2-(Alkynyl)aryl Isocyanates with Organoboron Reagents
A palladium(0)/monophosphine catalystpromotes a cyclization reaction of 2-(alkynyl)aryl isocyanates with organoboron reagents to produce stereodefined 3-alkylideneoxindoles. The alkynyl and isocyanato groups undergo oxidative cyclization with Pd(0) to form an oxapalladacycle intermediate. Subsequent transmetalation and reductive elimination afford the product.
Triflic acid-promoted cycloisomerization of 2-alkynylphenyl isothiocyanates and isocyanates: a novel synthetic method for a variety of indole derivatives
A new approach towards the synthesis of indolederivatives via triflic acid-promoted cycloisomerization with rearrangement of 2-(alkyn-1-yl)phenylisothiocyanates and 2-(alkyn-1-yl)phenylisocyanates has been achieved. By this methodology, structurally diverse types of indolederivatives such as thieno- and furo-indoles, spiro-indolethiones, spiro-oxindoles, and 3-alkylidene-oxindoles were synthesized
distinct reactions, the first, cyclization of 2-(alkynyl)aryl isocyanates with benzylic alcohols, and the second, [1,3] rearrangement of a benzyl group from oxygen to carbon, furnishing 3,3-disubstitutedoxindoles in one pot.
reaction occurred on treatment of 2-(alkynyl)aryl isocyanates with amides in the presence of a palladium(0)/diphosphine catalyst to stereoselectively form 3-(amidoalkylidene)oxindoles. A carbon−nitrogen bond as well as a carbon−carbon bond were simultaneously introduced onto the alkyne moiety to construct an oxindole skeleton with stereoselective placement of the amino substituent cis to the carbonyl group
A Bimetallic Catalyst and Dual Role Catalyst: Synthesis of <i>N</i>-(Alkoxycarbonyl)indoles from 2-(Alkynyl)phenylisocyanates
作者:Shin Kamijo、Yoshinori Yamamoto
DOI:10.1021/jo034254p
日期:2003.6.1
step proceeds with a cooperative catalytic activity of Pd and Cu. On the other hand, N-(alkoxycarbonyl)indoles are produced via the reaction of 2-(alkynyl)phenylisocyanates and alcohols under a catalytic amount of Na(2)PdCl(4) (5 mol %) or PtCl(2) (5 mol %). Pd(II) or Pt(II) catalyst exhibits dual roles; it acts as a Lewis acid to accelerate the addition of alcohols to isocyanates and as a typical transition-metal