28918-49-2Relevant academic research and scientific papers
A synthetic strategy using Witkop's pyrroloindole for (-)-debromoflustramine B, (+)-ent-debromoflustramine B and (+)-ent-debromoflustramide B
Cardoso, A. Sofia P.,Marques, M. Manuel B.,Srinivasan, Natarajan,Prabhakar, Sundaresan,Lobo, Ana M.
, p. 10211 - 10225 (2008/02/13)
While prenylation of (-)-Witkop's pyrroloindole (2), secured from l-tryptophan under standard N-alkylation conditions, led to a ca. 1:1 diastereoisomeric mixture of two C3a-alkylated indolenines 3 and 4, use of phase-transfer conditions altered this to ca. 1:2. Reduction followed by N-prenylation of the resulting secondary amines gave C,N-dialkylated products. The derived separable diastereoisomeric (-)- and (+)-Barton esters 19a and 19b were then converted into (-)-debromoflustramine B and (+)-ent-debromoflustramine B, respectively. A novel reaction involving oxygen and the carbanion derived from Barton ester 19b led to (+)-ent-debromoflustramide B. Treatment of N8-prenylated Witkop's pyrroloindole 5 with Lewis acid (BF3·Et2O) uncovered a new clean intramolecular cyclisation involving the prenyl unit.
A new synthesis of (-)-debromoflustramine B, (+)-ent-debromoflustramine B and (+)-debromoflustramide B
Cardoso,Srinivasan, Natarajan,Lobo, Ana M,Prabhakar, Sundaresan
, p. 6663 - 6666 (2007/10/03)
The first synthesis of (-)-debromoflustramine B is reported. Appropriate structural modifications of an optically pure Barton ester, obtained in five steps from N-acetyl-L-tryptophan methyl ester, lead to the alkaloid.
