title: Further exploration of the heterocyclic diversity accessible from the allylation chemistry of indigo.
abstract: Diversity-directed synthesis based on the cascade allylation chemistry of indigo, with its embedded 2,2'-diindolic core, has resulted in rapid access to new examples of the hydroxy-8a,13-dihydroazepino[1,2-a:3,4-b']diindol-14(8H)-one skeleton in up to 51% yield. Additionally a derivative of the novel bridged heterocycle 7,8-dihydro-6H-6,8a-epoxyazepino[1,2-a:3,4-b']diindol-14(13H)-one was produced when the olefin of the allylic substrate was terminally disubstituted. Further optimisation also produced viable one-pot syntheses of derivatives of the spiro(indoline-2,9'-pyrido[1,2-a]indol)-3-one (65%) and pyrido[1,2,3-s,t]indolo[1,2-a]azepino[3,4-b]indol-17-one (72%) heterocyclic systems. Ring-closing metathesis of the N,O-diallylic spiro structure and subsequent Claisen rearrangement gave rise to the new (1R,8aS,17aS)-rel-1,2-dihydro-1-vinyl-8H,17H,9H-benz[2',3']pyrrolizino[1',7a':2,3]pyrido[1,2-a]indole-8,17-(2H,9H)-dione heterocyclic system.
authors.affiliation: School of Chemistry, University of Wollongong, Wollongong, NSW, 2522, Australia.
authors.forename: Alireza
authors.initials: A
authors.lastname: Shakoori
authors.affiliation: School of Chemistry, University of Wollongong, Wollongong, NSW, 2522, Australia.
authors.forename: John B
authors.initials: JB
authors.lastname: Bremner
authors.affiliation: School of Chemistry, University of Wollongong, Wollongong, NSW, 2522, Australia.
authors.forename: Mohammed K
authors.initials: MK
authors.lastname: Abdel-Hamid
authors.affiliation: School of Chemistry, The Australian National University, Canberra, ACT 0200, Australia.
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Willis
authors.affiliation: National Centre for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), 113 Phaholyothin Road, Klong1, Klong Luang, Pathumanthani 12120, Thailand.
authors.forename: Rachada
authors.initials: R
authors.lastname: Haritakun
authors.affiliation: School of Chemistry, University of Wollongong, Wollongong, NSW, 2522, Australia.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Keller
keywords: allylation; cascade reactions; indigo; nitrogen heterocycles; rearrangement