A concise total synthesis of (+)-okaramine C

Abstract

The first total synthesis of (+)-okaramine C is described. Our previously described selenocyclisation-oxidative deselenation sequence was used to establish a 3a-hydroxy-pyrrolo[2,3-b]indole core, which was modified by selective epimerisation to the common pyrrolo[2,3-b]indole of the okaramines.

Reinvestigation of a Cyclic Dipeptide N‐Prenyltransferase Reveals Rearrangement of N‐1 Prenylated Indole Derivatives

“…Signals for the four protons at positions 4, 5, 6 and 7 of the indole ring were clearly observed (Table S1), and revealed that the prenyl moiety is connected to N-1 or C-2 of the indole ring. The signals of the methyl groups in the reverse prenyl moieties attached to C-2 of the indole rings of some diketopiperazine derivatives, for example, in echnulin-and isoechinulin-type alkaloids, [2][3][4] in deoxybrevianamide E [5] or okaramines, [6,7] were usually found in the range of 1.40 to 1.55 ppm. In comparison, the signals of the methyl groups in the prenyl moieties of the enzymatic products of CdpNPT are significantly up-field shifted to 0.9 to 1.1 ppm.…”

Frontier studies on highly selective bio-regulators useful for environmentally benign agricultural production

“…The convergent total synthesis of (+)-okaramine J (10) was achieved by Roe et al in 2003. 10) The first enantioselective total synthesis of a member of the okaramine family, okaramine N (14), was accomplished by Baran et al in 2003. 11) In 2004, the total synthesis of okaramine C (3) was completed by Hewitt et al 12) All stereoisomers of okaramine M were synthesized by Iizuka et al and the reported structure of okaramine M (13a) was revised to 13b. …”

Structure, Bioactivity and Synthesis of Natural Products with Hexahydropyrrolo[2,3‐b]indole

“…Isoprenyl group was afforded after partial reduction of the alkyne introduced by N 8 -alkylation using 2-bromo-2-methylbut-3-yne. [129] Alkylative cyclization Cyclization with electrophiles (A, Scheme 5): This procedure uses the reactivity of indole nucleous of tryptamine or tryptophan with alkylating agents over the substituted 3-position, followed by in situ capture of the resulting indoline by the protected lateral amine.…”

“…Total synthesis of (+)-okaramine C (11). [129] [133] (AE )-debromoflustramides B and E and (AE )-debromoflustramines B and E have been prepared using this procedure. [134] Nakagawa et al synthesized (AE )-esermethole (112) using an alkylative cyclization.…”