Synthetic studies towards bruceantin. Part 2. The synthesis of a pentacyclic intermediate

1991 ◽  
Vol 69 (4) ◽  
pp. 723-731 ◽  
Author(s):  
Sultan Darvesh ◽  
Andrew S. Grant ◽  
David I. MaGee ◽  
Zdenek Valenta
Keyword(s):  
Key Words ◽  
Michael Reaction ◽  
Sigmatropic Rearrangement ◽  
Synthetic Approach ◽  
Forming Strategy ◽  
Acid Catalyzed ◽  
Synthetic Studies ◽  
Key Steps

In a synthetic approach to the quassinoid bruceantin (2), the key intermediate 8 obtained via alkylation of a dianion has been transformed into the pentacyclic intermediate 33 via an ABDC ring forming strategy. The key steps involved in this route are as follows: a unique acid catalyzed cyclization, 19 → 20; an intramolecular Michael reaction, 24 → 28; and an allyl sulfoxide [2,3]-sigmatropic rearrangement to introduce the axial C12 alcohol, 31 → 33. Key words: bruceantin, quassinoids, cyclization, sulfoxides, sigmatropic rearrangement.

scholarly journals A synthetic approach to resistomycin

1977 ◽  
Vol 55 (5) ◽  
pp. 785-791 ◽  
Author(s):  
John F. Kingston ◽  
Larry Weiler
Keyword(s):  
Synthetic Approach ◽  
Synthetic Route ◽  
Acid Catalyzed ◽  
Key Steps

An outline of a synthetic route to the antibiotic resistomycin is presented. We report the successful construction of an intermediate containing all of the carbon atoms in resistomycin with requisite functionalities. The key steps involved an aldol type condensation of the dianion from 2,4,6-trimethoxybenzoylacetone and a suitable acetophenone. This was followed by a novel acid-catalyzed cyclization–condensation to form the naphthalene intermediate required in our scheme.

scholarly journals Total Synthesis of Oxepin and Dihydrooxepin Containing Natural Products

Synthesis ◽  
2021 ◽  
Author(s):  
Thomas Magauer ◽  
Kevin Rafael Sokol
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Natural Product ◽  
Radical Cyclization ◽  
Sigmatropic Rearrangement ◽  
Natural Product Synthesis ◽  
Synthetic Methods ◽  
Acid Catalyzed ◽  
Metal Catalyzed ◽  
Key Steps

AbstractThe construction of oxepin and dihydrooxepin containing natural products represents a challenging task in total synthesis. In the last decades, a variety of synthetic methods have been reported for the installation of these structural motifs. Herein, we provide an overview of synthetic methods and strategies to construct these motifs in the context of natural product synthesis and highlight the key steps of each example.1 Introduction2 Oxepin Natural Products3 Dihydrooxepin Natural Products3 Brønsted or Lewis acid Catalyzed Cyclization3.2 Radical Cyclization3.3 Substitution and Addition Cyclization3.4 Sigmatropic Rearrangement3.5 Oxidative Methods3.6 Transition Metal Catalyzed Cyclization4 Summary

scholarly journals Tackling Pristinamycin IIB Problems: Synthetic Studies toward Some Fluorinated Analogs

2020 ◽  
Vol 3 (1) ◽  
pp. 107
Author(s):  
Assia Chebieb ◽  
Chewki Ziani-Cherif
Keyword(s):  
Chemical Structure ◽  
Wittig Reaction ◽  
Antimicrobial Agents ◽  
Synthetic Approach ◽  
Solubility In Water ◽  
Fluorinated Analogs ◽  
Human Therapy ◽  
Primary Structures ◽  
Synthetic Studies

Streptogramins are potent antibiotics against numerous highly resistant pathogens and therefore are used in last-resort human therapy. These antibiotics are formed of both A- and B-group compounds named pristinamycins that differ in their basic primary structures. Although pristinamycin IIB is among the most interesting antibiotics in this family, it presents numerous problems related to its chemical structure, such as instability at most pH levels, weak solubility in water, and resistance by bacteria. As a response to the need for developing new antimicrobial agents, we have designed a new analog of pristinamycin IIB, based most importantly on the introduction of fluorine atoms. We conjectured indeed that the introduced modifications may solve the above-mentioned problems exhibited by pristinamycin IIB. Our multistep synthetic approach relies on few key reactions, namely a Wittig reaction, a Grubbs reaction, and dihydroxy, -difluoro API (Advanced Pharmaceutical Intermediate) synthesis

Enantioselective Synthesis of the Sex Pheromone of Lichen Moth, Miltochrista calamine, and Its Diastereomer

Synlett ◽  
2021 ◽  
Author(s):  
Jiangchun Zhong ◽  
Gucheng Yuan ◽  
Jiawei Liu ◽  
Shihang Yu ◽  
Xueyang Wang ◽  
...  
Keyword(s):  
Sex Pheromone ◽  
Enantioselective Synthesis ◽  
Synthetic Approach ◽  
Chiral Auxiliaries ◽  
Synthetic Sex Pheromone ◽  
Key Steps

AbstractThe synthesis of a Miltochrista calamine sex pheromone and its diastereomer has been developed. The key steps of the synthetic approach involved Evans’ chiral auxiliaries and the addition of alkyne to aldehyde, which were firstly applied to prepare this sex pheromone and its diastereomer. The synthetic sex pheromone could be used to trap insects and study physiological and ecological questions of the lichen moth.

Brønsted Acid-catalyzed Dynamic Kinetic Resolution of in situ Formed Acyclic N,O-hemiaminals: Cascade Synthesis of Chiral Cyclic N,O-aminals

2021 ◽  
Author(s):  
Xue-Jiao Lv ◽  
Yong-Chao Ming ◽  
Hui-Chun Wu ◽  
Yankai Liu
Keyword(s):  
Kinetic Resolution ◽  
Michael Reaction ◽  
Amide Group ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Dynamic Kinetic Resolution ◽  
Brönsted Acid ◽  
Acid Catalyzed

A Brønsted acid-catalyzed cascade acyclic N,O-hemiaminal formation/oxa-Michael reaction is developed for the synthesis of cis-2,6-disubstituted tetrahydropyrans bearing an exo amide group, that is, cyclic N,O-aminals. By using TsOH, various different...

Synthetic Studies towards the Total Synthesis of Indole Alkaloids Containing Indolyl Lactam Frameworks

Synlett ◽  
2020 ◽  
Author(s):  
Fu-She Han ◽  
Dong-Xing Tan
Keyword(s):  
Total Synthesis ◽  
Indole Alkaloids ◽  
Cycloaddition Reaction ◽  
Terminal Olefin ◽  
Asymmetric Reaction ◽  
Rapid Construction ◽  
Fused Ring ◽  
Acid Catalyzed ◽  
Synthetic Studies ◽  
Type Substitution

AbstractIn this account, recent progress on the synthetic studies of several monoterpene indole alkaloids, (±)-mersicarpine, misassigned (±)-tronoharine, and (±)-leuconodines D and E, is summarized. Specifically, the rationale for the design and development of the Lewis acid catalyzed SN1-type substitution and formal [3+3] cycloaddition reaction of indol-2-yl carbinols, and the Pd-catalyzed aerobic oxidative intramolecular Heck cross-coupling of indolyl amides tethered with a terminal olefin functionality, are emphasized. These key reactions set the basis for the rapid construction of the fused ring skeleton containing an all-carbon quaternary center at the indol-2-yl position.1 Introduction2 Synthetic Study of (±)-Mersicarpine3 Synthetic Study of the Misassigned (±)-Tronoharine4 Study of the Asymmetric Reaction of Indol-2-yl Carbinols5 Synthetic Study of (±)-Leuconodines D and E6 Conclusion

Sign in / Sign up

Export Citation Format

Share Document