Title
Synthesis of 3-substituted benzo[g]isoquinoline-5,10-diones : a convenient one-pot Sonogashira coupling/iminoannulation procedure Synthesis of 3-substituted benzo[g]isoquinoline-5,10-diones : a convenient one-pot Sonogashira coupling/iminoannulation procedure
Author
Faculty/Department
Faculty of Sciences. Chemistry
Publication type
article
Publication
Oxford ,
Subject
Chemistry
Source (journal)
Tetrahedron. - Oxford
Volume/pages
67(2011) :12 , p. 2269-2278
ISSN
0040-4020
0040-4020
ISI
000288778100011
Carrier
E
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
Abstract
A series of 3-substituted 5,10-dimethoxybenzo[g]isoquinolines were prepared by coupling of terminal alkynes with the tert-butylimine of 3-bromo-1,4-dimethoxy-2-naphthaldehyde in the presence of a Pd-catalyst and subsequent Cu-catalyzed cyclization of the intermediate 3-alkynyl-2-naphthylcarbaldehyde. A CAN-mediated oxidative demethylation yielded the corresponding 2-azaanthraquinones in excellent yields. Since this methodology proved to be limited to alkynes bearing aromatic groups, an alternative and more general Pd-catalyzed coupling procedure was developed, starting from 3-bromo-1,4-dimethoxy-2-naphthaldehyde. For more acidic terminal alkynes, like phenylacetylene, a combination of Pd(OAc)2/P(t-Bu)3/CuI (2/6/1) with potassium carbonate in DMF gave a complete conversion within 24 h. For less acidic acetylenes, 2 equiv of alkyne and caesium carbonate as a base were required in order to obtain complete conversion of the starting material within 24 h. These altered Sonogashira conditions also allowed the isolation of a benzo[f]indenone as an interesting side product in case Bu4NCl was added to the reaction mixture. The 3-alkynyl-1,4-dimethoxy-2-naphthaldehyde acquired after completion of the Pd-catalyzed coupling could be cyclized by adding a solution of ethanolic ammonia and an extra equivalent of potassium carbonate to the reaction mixture. As such, this consecutive one-pot coupling/iminoannulation procedure was a convenient alternative to the Larock isoquinoline procedure, enabling the isolation of a series of 3-substituted 5,10-dimethoxybenzo[g]isoquinolines.
E-info
https://repository.uantwerpen.be/docman/iruaauth/51c174/a20391c8270.pdf
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000288778100011&DestLinkType=RelatedRecords&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000288778100011&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000288778100011&DestLinkType=CitingArticles&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
Handle