Procedure—economical enantioselective total syntheses of asperlicins C and E

Isolation, chemistry, and biology of pyrrolo[1,4]benzodiazepine natural products

The isolation of the antitumor antibiotic anthramycin in the 1960s prompted extensive research into pyrrolo[1,4]benzodiazepines (PBD) as potential therapeutics for the treatment of cancers. Since then, nearly 60 PBD natural products have been isolated and evaluated with regard to their biological activity. Synthetic studies and total syntheses have enabled access to PBD analogues, culminating in the development of highly potent anticancer agents. This review provides a summary of the occurrence and biological activity of PBD natural products and covers the strategies employed for their total syntheses.

Procedure-Economical, Enantioselective Total Syntheses of Polycyclic Natural Products and Analogues Containing a 3a-Hydroxyhexahydropyrrolo[2,3-b]indole-2-carboxylic Acid Residue

The 3a-hydroxyhexahydropyrrolo[2,3-b]indole-2-carboxylic acid (HPIC) residue and its aza-analogue are found in many bioactive natural products. In this account, short divergent total syntheses of several such natural products, diastereomers and analogues are described. It is demonstrated that by appropriate combination of different efficient tactics such as biomimetic/bio-inspired synthesis, chemo/regioselective reactions, umpolung of regioselectivity and/or reactivity, and tandem reactions, the enantioselective syntheses of polycyclic molecules such as (+)-asperlicin E and (–)-robustanoids A and B can be achieved in a protecting-group-free and redox-economical manner, in only three to four steps starting from l-tryptophan.

1 Introduction

2 Strategic Considerations

2.1 Occurrence of HO-HPIC and HO-aza-HPIC Residues in Natural Products

2.2 Biosyntheses of HO-HPIC and HO-aza-HPIC Residues

2.3 Chemical Syntheses of HO-HPIC and HO-aza-HPIC Residues

3 Procedure-Economical Syntheses of HO-HPIC-Containing Natural Products

3.1 Protecting-Group-Free Syntheses of Asperlicin E, Its Diastereomer, and an Analogue

3.2 Divergent Syntheses of (–)-Robustanoids A and B, a Diastereomer, and Analogues

4 Conclusion and Future Perspectives

One-pot synthesis of N-heterocycles and enimino carbocycles by tandem dehydrative coupling–reductive cyclization of halo-sec-amides and dehydrative cyclization of olefinic sec-amides

We report a versatile approach for the one-pot synthesis of substituted pyrrolidine, piperidine, indolizidine, and quinolizidine ring systems, and enimino carbocycles.

Stereodivergent and enantioselective total syntheses of isochaetominines A–C and four pairs of isochaetominine C enantiomers: a six-step approach

We report the first total syntheses of (−)-isochaetominines A–C and eight 2,3-cis-stereoisomers of isochaetominine C, and structural revisions of (−)-pseudofischerine and (−)-aniquinazoline D.

Aza-Knoevenagel-type condensation of secondary amides: direct access to N-monosubstituted β,β-difunctionalized enamines

An efficient approach toN-monosubstituted β,β-difunctionalized enamines, a class of versatile building blocks for the synthesis of bioactive compounds, is reported.

Recent developments in the chemistry of quinazolinone alkaloids

This review focuses on the recent advances in the chemistry of quinazolinone alkaloids which covers the newly isolated quinazolinone alkaloids with their biological activities and the recently reported total syntheses of quinazolinone alkaloids from 2006 to 2015.