Heterocycle Construction: The Chang Synthesis of Louisianin C

Abstract

It has been known for some time that an acid chloride 1 can be added to an alkyne 2 to give the β-chloro enone. Yasushi Tsuji of Kyoto University found (J. Am. Chem. Soc. 2009, 131, 6668) that with an Ir catalyst, the condensation of 1 with 2 could be directed to the furan 3. Huanfeng Jiang of the South China University of Technology described (Organic Lett. 2009, 11, 1931) a complementary route to furans, Cu-mediated condensation of a propargyl alcohol 4 with the diester 5 to give 6. Bruce A. Arndtsen of McGill University developed (Organic Lett. 2009, 11, 1369) an approach to pyrroles such as 9, by condensation of an α,β-unsaturated α-cyano imine 7 with the acid chloride 8. Thomas J. J. Müller of Heinrich-Heine-Universität Düsseldorf observed (Organic Lett. 2009, 11, 2269) the condensation of an acid chloride 11 with a propargyl amine 10, leading to the iodo pyrrole 12. John A. Murphy of the University of Strathclyde uncovered (Tetrahedron Lett. 2009, 50, 3290) a new entry to the Fischer indole synthesis, by Petasis homologation of a hydrazide 13. Dali Yin of Peking Union Medical College took advantage (Organic Lett. 2009, 11, 637) of the easy sequential displacement of the fluorides of 15, leading, after acid-catalyzed cyclization, to the indole 17. Kang Zhao of Tianjin University extended (Organic Lett. 2009, 11, 2417; Organic Lett. 2009, 11, 2643) his studies of oxidation of an enamine 18 to the 2H -azirine, that on heating cyclized to the indole 19. Peter Wipf of the University of Pittsburgh established (Chem. Commun. 2009, 104) a microwave-promoted indole synthesis, illustrated by the intramolecular Diels-Alder cyclization of 20 to 21. A review delineating all nine types of indole syntheses will appear shortly in Angewandte Chemie . Fushun Liang and Qun Liu of Northeast Normal University demonstrated (J. Org. Chem. 2009, 74, 899) that the readily-prepared ketene thioacetal 22 condensed with NH3 to give the pyridine 23. Sundaresan Prabhakar and Ana M. Lobo of the New University of Lisbon observed (Tetrahedron Lett. 2009, 50, 3446) that the addition of the alkoxy propargyl amine to the alkyne 25 gave a Z alkene, that on warming rearranged to the pyridine 26.