Synthesis of (−)-(R)-angustureine by formal alkynylation of a chiral β-amino ester

Mitsunobu reaction: assembling C-N bonds in chiral traditional Chinese medicine

The synthesis of chiral molecules has long been a central focus and challenge in medicinal chemistry research. The Mitsunobu reaction, developed by Japanese chemist Mitsunobu in 1967, is a widely utilized bimolecular nucleophilic substitution reaction that plays a vital role in synthesizing chiral natural products. In this reaction, alcohols react with nucleophilic reagents in the presence of a phosphine ligand to form an intermediate phosphonium salt. This intermediate enables the formation of various chemical bonds. The purpose of this review is to explore the applications of the Mitsunobu chemistry in constructing pivotal carbon-nitrogen bonds in traditional Chinese medicines (TCMs). Emphasis will be placed on the preparative synthetic applications of the Mitsunobu strategy as a key step in the total synthesis of naturally occurring biologically active products.

An intramolecular C-N cross-coupling of β-enaminones: a simple and efficient way to precursors of some alkaloids of Galipea officinalis

2-Aroylmethylidene-1,2,3,4-tetrahydroquinolines with the appropriate substituents can be suitable precursors for the synthesis of alkaloids from Galipea officinalis (cuspareine, galipeine, galipinine, angustureine). However, only two, rather low-yielding procedures for their synthesis are described in the literature. We have developed a simple and efficient protocol for an intramolecular, palladium or copper-catalysed amination of both chloro- and bromo-substituted 3-amino-1,5-diphenylpent-2-en-1-ones leading to the above-mentioned tetrahydroquinoline moiety. The methodology is superior to the methods published to date.

An enantioselective approach to 2-alkyl substituted tetrahydroquinolines: total synthesis of (+)-angustureine

A simple and highly efficient synthetic approach to enantiopure 2-alkyl substituted tetrahydroquinoline 1 skeleton from aldehydes as starting materials and its application to the total synthesis of (+)-angustureine 2 is described.