The synthesis of chasmanine: aromatic intermediate

Abstract

The stereospecific total synthesis of the pentacyclic tetrasubstituted intermediate 39 is described. The conversion of this material to the delphinine type alkaloid chasmanine IV by the method worked out recently by the same group (1) is envisaged.

Systematic Investigation of Lipophilicity Modulation by Aliphatic Fluorination Motifs

“…1 H NMR (400 MHz, CDCl 3 ) δ 7.50–7.43 (m, 6H, H Ar ), 7.34–7.27 (m, 6H, H Ar ), 7.26–7.20 (m, 3H, H Ar ), 5.86 (ddt, J = 17.1, 10.2, 6.8 Hz, 1H, H3), 5.13–4.98 (m, 2H, H4), 3.13 (t, J = 6.8 Hz, 2H, H1), 2.38 (q, J = 6.8 Hz, 2H, H2) ppm; 13 C­{ 1 H} NMR (101 MHz, CDCl 3 ) δ 144.3 (C Ar × 3), 135.6 (C3), 128.7 (C Ar × 6), 127.7 (C Ar × 6), 126.9 (C Ar × 3), 116.3 (C4), 86.4 ( C Ph 3 ), 63.2 (C1), 34.6 (C2) ppm; IR (neat) 3058 (w), 2924 (w), 1448 (s), 1068 (s), 695 (s) cm –1 ; HRMS (EI) for C 23 H 22 O [M •+ ], calculated 314.16652, found 314.16555. 1 H NMR data are consistent with the literature …”

“…To a solution of 3-buten-1-ol 42 (0.80 g, 1 equiv) and pyridine (1.35 1 H NMR data are consistent with the literature. 101 1-Trityloxy-3,5,5,5-tetrafluoropentane (44). To a solution of Selectfluor (6.08 g, 3 equiv) in DMF (70 mL) was added PhI(OAc) 2 (1.85 g, 1 equiv), AgOTf (2.94 g, 2 equiv), and CsF (1.73 g, 2 equiv) at −50 °C.…”

A new synthesis of chasmanine and 13-desoxydelphonine: a preferred route to the aromatic intermediate

“…The aldehyde 19 was treated with an excess of 3-benzyloxy-4-methoxy-11-butyl magnesium bromide (9) and the mixture of the epimeric alcohols 20 was obtained in a yield of 87%. For purposes of characterization and analysis, the subsequent epimeric mixtures were separated by preparative thin layer chromatography (see Experimental).…”

Total Synthesis, Relay Synthesis, and Structural Confirmation of the C18-Norditerpenoid Alkaloid Neofinaconitine

“…The structure of the C19-norditerpenoid alkaloids was first elucidated by Wiesner and co-workers, who also completed the first total synthesis of a member of this group, talatisamine ( 4 ) . They subsequently also achieved the total syntheses of chasmanine ( 5 ) and 13-deoxydelphonine ( 6 ) , via an alternative strategy that provided improved chemoselectivity at key steps. Despite numerous other attempts, these remain the only published total syntheses of norditerpenoid alkaloids to date.…”