Synthesis of schumanniophytine and isoschumanniophytine

Abstract

Some controversy has surrounded the structures of the Schumanniophyton alkaloids schumanniophytine and isoschumanniophytine. In 1978 Schlittler and Spitaler described1 the isolation of an alkaloid which they named schumanniophytine and to which they assigned structure 1. In 1985 Houghton and Yang reported2 the isolation of

The Directed Ortho Metallation (DoM)–Cross‐Coupling Nexus. Synthetic Methodology for the Formation of Aryl–Aryl and Aryl–Heteroatom–Aryl Bonds

“…Taking advantage of nucleophilic heteroaromatic substitution (see also Scheme 14.43,224), NaH treatment leads to the indolo-annelated product 187 [153]. In an alternative approach, in which the α-carboline ring construction is the key step, the simple iodoindole 188 [155]. The construction of the indolocarbazole alkaloid, eudistomin U 223, is instructive from the perspective of not only the combined DoM-Negishi cross-coupling but also an additional synthetic link to nucleophilic aromatic substitution (S N Ar) (Scheme 14.43) [159].…”

Chemistry of 3-carbonyl-2-methyl-4-oxo-4H-1-benzopyrans

“…For example, 5,7-dihydroxy-2-methylchromone 61, needed for the synthesis of schumanniophytine and isoschumanniophytine, has been prepared by Na 2 CO 3 -H 2 O treatment of the 3-acetylchromone 60, obtainable from phloracetophenone 29b and Ac 2 O-AcONa. 33 The chromone 62b obtained by similar deacetylation of 3-acetylchromone 62a is treated with I 2 -CF 3 CO 2 Ag to afford 3-iodochromone 62c; the latter (62c) on Suzuki coupling with arylboronic acid leads to 3-aryl-2-methylchromones 62d (Ar = Ph, 4-ClC 6 H 4 , 4-MeOC 6 H 4 , 2-naphthyl, C 6 H 4 Ph etc.). …”

Furyl analogs of α-pyrono[2,3-f]isoflavones with an azole substituent in the α-pyrone nucleus

“…It enters into the composition of the pyridylchromone alkaloid schumanniophytin, isolated from the roots and bark of Schumanniophyton magnificum and S. problematicum [5][6][7].It is known that α-pyrono[2,3-f]flavones and isoflavones display bactericidal activity [8]. The same activity is also found for 2-hetarylpyrano[2,3-f]chromene-4,8-diones, including furyl analogs of α-pyrono-[2,3-f]flavones [9], which arouses interest in heterocyclic derivatives of this system.…”