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

Synlett ◽  
2020 ◽  
Vol 31 (17) ◽  
pp. 1681-1690
Author(s):  
Pei-Qiang Huang
Keyword(s):  
Natural Products ◽  
Carboxylic Acid ◽  
Tandem Reactions ◽  
Protecting Group ◽  
Future Perspectives ◽  
Total Syntheses ◽  
Bioactive Natural Products ◽  
Regioselective Reactions ◽  
Enantioselective Syntheses

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 Introduction2 Strategic Considerations2.1 Occurrence of HO-HPIC and HO-aza-HPIC Residues in Natural Products2.2 Biosyntheses of HO-HPIC and HO-aza-HPIC Residues2.3 Chemical Syntheses of HO-HPIC and HO-aza-HPIC Residues3 Procedure-Economical Syntheses of HO-HPIC-Containing Natural Products3.1 Protecting-Group-Free Syntheses of Asperlicin E, Its Diastereomer, and an Analogue3.2 Divergent Syntheses of (–)-Robustanoids A and B, a Diastereomer, and Analogues4 Conclusion and Future Perspectives

scholarly journals Protecting group free enantiospecific total syntheses of structurally diverse natural products of the tetrahydrocannabinoid family

2015 ◽  
Vol 51 (14) ◽  
pp. 2871-2873 ◽  
Author(s):  
Dattatraya H. Dethe ◽  
Rohan D. Erande ◽  
Samarpita Mahapatra ◽  
Saikat Das ◽  
Vijay Kumar B.
Keyword(s):  
Natural Products ◽  
Lewis Acid ◽  
Allylic Alcohol ◽  
Protecting Group ◽  
Total Syntheses ◽  
Acid Catalyzed

A simple, highly diastereoselective, Lewis acid catalyzed Friedel–Crafts coupling of a cyclic allylic alcohol with resorcinol derivatives has been developed.

Total syntheses of polyketide-derived bioactive natural products

2006 ◽  
Vol 6 (4) ◽  
pp. 217-233 ◽  
Author(s):  
Kuniaki Tatsuta ◽  
Seijiro Hosokawa
Keyword(s):  
Natural Products ◽  
Total Syntheses ◽  
Bioactive Natural Products

Total Syntheses of Polyketide-Derived Bioactive Natural Products

ChemInform ◽  
2007 ◽  
Vol 38 (11) ◽  
Author(s):  
Kuniaki Tatsuta ◽  
Seijiro Hosokawa
Keyword(s):  
Natural Products ◽  
Total Syntheses ◽  
Bioactive Natural Products

Advances in catalytic and protecting-group-free total synthesis of natural products: a recent update

2020 ◽  
Vol 56 (61) ◽  
pp. 8569-8590 ◽  
Author(s):  
Rodney A. Fernandes ◽  
Praveen Kumar ◽  
Priyanka Choudhary
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Protecting Group ◽  
Feature Article ◽  
Total Syntheses

This feature article highlights the recently achieved efficient total syntheses of many natural products based on catalytic steps and protecting-group-free strategies, leading to overall economy and efficiency in synthesis.

scholarly journals Unexpected Racemization in the Course of the Acetalization of (+)-(S)-5-Methyl-Wieland–Miescher Ketone with 1,2-Ethanediol and TsOH under Classical Experimental Conditions

2019 ◽  
Vol 20 (24) ◽  
pp. 6147
Author(s):  
Francesca Leonelli ◽  
Irene Piergentili ◽  
Giulio Lucarelli ◽  
Luisa Maria Migneco ◽  
Rinaldo Marini Bettolo
Keyword(s):  
Natural Products ◽  
Experimental Conditions ◽  
Enantiomerically Pure ◽  
Bioactive Natural Products ◽  
Classical Procedure ◽  
Enantioselective Syntheses

(+)-(S) and (−)-(R)-5-methyl-Wieland-Miescher ketone (+)-1 and (−)-1, are important synthons in the diastereo and enantioselective syntheses of biological and/or pharmacological interesting compounds. A key step in these syntheses is the chemoselective C(1)O acetalization to (+)-5 and (−)-5, respectively. Various procedures for this transformation have been described in the literature. Among them, the classical procedure based on the use of 1,2-ethanediol and TsOH in refluxing benzene in the presence of a Dean-Stark apparatus. Within our work on bioactive natural products, it occurred to us to observe the partial racemization of (+)-5 in the course of the acetalization of (+)-1 by means of the latter methodology. Aiming to investigate this drawback, which, to our best knowledge, has no precedents in the literature, we acetalized with 1,2-ethanediol and TsOH in refluxing benzene and in the presence of a Dean–Stark apparatus under various experimental conditions, enantiomerically pure (+)-1. It was found that the extent of racemization depends on the TsOH/(+)-1 and 1,2-ethanediol/(+)-1 ratios. Mechanism hypotheses for this partial and unexpected racemization are provided.

Total Syntheses of Bioactive Natural Products from Carbohydrates

ChemInform ◽  
2007 ◽  
Vol 38 (12) ◽  
Author(s):  
Kuniaki Tatsuta ◽  
Seijiro Hosokawa
Keyword(s):  
Natural Products ◽  
Total Syntheses ◽  
Bioactive Natural Products
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