Annulation via donor-acceptor reagents. An efficient total synthesis of (±)-∆9(12)-capnellene

1984 ◽  
Vol 62 (3) ◽  
pp. 629-631 ◽  
Author(s):  
E. Piers ◽  
V. Karunaratne
Keyword(s):  
Total Synthesis ◽  
Grignard Reagent ◽  
Conjugate Addition ◽  
Intramolecular Alkylation ◽  
Racemic Form ◽  
Donor Acceptor ◽  
Key Steps

A short, efficient total synthesis of the racemic form of the marine sesquiterpenoid (-)-∆9(12)-capnellene (1) is described. The key steps of the synthesis are two methylenecyclopentane annulation sequences (14 → 16; 22 → 24) involving the CuBr-Me2S→BF3 • Et2O catalyzed conjugate addition of the Grignard reagent 13 to the enones 14 and 22, followed by intramolecular alkylation (KH, tetrahydrofuran) of the resultant adducts 15 and 23, respectively

scholarly journals Asymmetric total synthesis of a putative sex pheromone component from the parasitoid wasp Trichogramma turkestanica

2014 ◽  
Vol 10 ◽  
pp. 761-766 ◽  
Author(s):  
Danny Geerdink ◽  
Jeffrey Buter ◽  
Teris A van Beek ◽  
Adriaan J Minnaard
Keyword(s):  
Sex Pheromone ◽  
Total Synthesis ◽  
Parasitoid Wasp ◽  
Conjugate Addition ◽  
Enantioselective Synthesis ◽  
Pheromone Component ◽  
Asymmetric Total Synthesis ◽  
Catalytic Asymmetric ◽  
Key Steps

Virgin females of the parasitoid wasp Trichogramma turkestanica produce minute amounts of a sex pheromone, the identity of which has not been fully established. The enantioselective synthesis of a putative component of this pheromone, (6S,8S,10S)-4,6,8,10-tetramethyltrideca-2E,4E-dien-1-ol (2), is reported as a contribution to this identification. Catalytic asymmetric conjugate addition of methylmagnesium bromide and stereoselective Horner–Wadsworth–Emmons olefinations are used as the key steps, and 2 was obtained in 16 steps with an overall yield of 4.4%.

Bifunctional conjunctive reagents: 5-chloro-2-lithio-1-pentene and related substances. A methylenecyclohexane annulation method

1993 ◽  
Vol 71 (3) ◽  
pp. 280-286 ◽  
Author(s):  
Edward Piers ◽  
Bik Wah Anissa Yeung ◽  
Fraser F. Fleming
Keyword(s):  
Grignard Reagent ◽  
Conjugate Addition ◽  
The Novel ◽  
Intramolecular Alkylation ◽  
Related Substances ◽  
Cyclic Enones

The development of a new, synthetically useful methylenecyclohexane annulation method is described. Transmetallation (MeLi, tetrahydrofuran, −78 °C) of 5-chloro-2-trimethylstannyl-1-pentene (8) affords the novel bifunctional reagent 5-chloro-2-lithio-1-pentene (9), which, at temperatures higher than approximately −50 °C, self-destructs to give methylenecyclobutane (14). Reagent 9 can be converted into the Grignard reagent 10 and the organocopper(I) species 15. Conjugate addition of 10 and 15 to a number of cyclic enones (16–22), followed by intramolecular alkylation of the resultant adducts (23–29), produces the corresponding methylenecyclohexane annulation products (30–40).

scholarly journals A Convenient Synthesis of the Central Core of Helioporins, seco-Pseudopterosins and Pseudopterosins via BCA-Annulation Sequence

2008 ◽  
Vol 3 (4) ◽  
pp. 1934578X0800300
Author(s):  
Gema Esteban ◽  
Rocío Rincón ◽  
Aurelio G. Csákÿ ◽  
Joaquín Plumet
Keyword(s):  
Suzuki Coupling ◽  
Conjugate Addition ◽  
Ring Formation ◽  
Central Core ◽  
Racemic Form ◽  
Convenient Synthesis ◽  
Key Steps

A convenient synthesis of the central core of helioporins, seco-pseudopterosins and pseudopterosins in racemic form is reported, using a Suzuki coupling (A-ring formation)-Friedel-Crafts acylation sequence, followed by synthetic elaboration of the resulting tetralone derivative. Key steps of the method are a totally diastereoselective cuprate conjugate addition and a final, spontaneous Friedel-Crafts acylation.

Concise Total Synthesis of Curvulone B

Synlett ◽  
2020 ◽  
Author(s):  
Debendra K. Mohapatra ◽  
Shivalal Banoth ◽  
Utkal Mani Choudhury ◽  
Kanakaraju Marumudi ◽  
Ajit C. Kunwar
Keyword(s):  
Total Synthesis ◽  
Stereoselective Synthesis ◽  
Ring System ◽  
Bond Forming ◽  
Cross Metathesis ◽  
Bond Forming Reactions ◽  
Key Steps

AbstractA concise and convergent stereoselective synthesis of curvulone B is described. The synthesis utilized a tandem isomerization followed by C–O and C–C bond-forming reactions following Mukaiyama-type aldol conditions for the construction of the trans-2,6-disubstituted dihydropyran ring system as the key steps. Other important features of this synthesis are a cross-metathesis, epimerization, and Friedel–Crafts acylation.

First Total Synthesis of a Fluorinated Calystegin

2010 ◽  
Vol 65 (4) ◽  
pp. 445-451 ◽  
Author(s):  
René Csuk ◽  
Erik Prell ◽  
Stefan Reißmann ◽  
Claudia Korb
Keyword(s):  
Total Synthesis ◽  
Ring Opening ◽  
Competitive Inhibitor ◽  
Ring Closure ◽  
Target Compound ◽  
Metathesis Reaction ◽  
Grubbs Catalyst ◽  
Ring Opening Reaction ◽  
Ultrasound Assisted ◽  
Key Steps

A straightforward chiral pool synthesis for the first fluorinated calystegin is described. Key steps of this synthesis include an ultrasound-assisted Zn-mediated tandem ring opening reaction followed by a Grubbs’ catalyst-mediated ring closure metathesis reaction. The target compound is a selective and competitive inhibitor for a β -glycosidase.

Total Synthesis of (±)-α- and β-Lycoranes by Sequential Chemoselective Conjugate Addition−Stereoselective Nitro-Michael Cyclization of an ω-Nitro-α,β,ψ,ω-unsaturated Ester

2003 ◽  
Vol 5 (7) ◽  
pp. 1123-1126 ◽  
Author(s):  
Tomohisa Yasuhara ◽  
Katsumi Nishimura ◽  
Mitsuaki Yamashita ◽  
Naoshi Fukuyama ◽  
Ken-ichi Yamada ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Conjugate Addition ◽  
Unsaturated Ester

scholarly journals Total syntheses of all tri-oxygenated 16-phytoprostane classes via a common precursor constructed by oxidative cyclization and alkyl–alkyl coupling reactions as the key steps

2017 ◽  
Vol 15 (44) ◽  
pp. 9408-9414 ◽  
Author(s):  
Jakub Smrček ◽  
Radek Pohl ◽  
Ullrich Jahn
Keyword(s):  
Total Synthesis ◽  
Oxidative Cyclization ◽  
Coupling Reactions ◽  
Total Syntheses ◽  
Common Precursor ◽  
Key Steps

A parallel total synthesis of 16-F1t-, 16-E1-phytoprostanes and a first synthesis of 16-D1t-phytoprostanes based on a common precursor are described.

scholarly journals Oxazolidinones as Chiral Auxiliaries in the Asymmetric 1,4-Conjugate Addition Reaction Applied to the Total Synthesis of Natural Products: A Supplemental Mini-Review

2018 ◽  
Vol 15 (1) ◽  
pp. 3-20 ◽  
Author(s):  
Vahideh Zadsirjan ◽  
Majid M. Heravi
Keyword(s):  
Total Synthesis ◽  
Biological Activities ◽  
Conjugate Addition ◽  
Chiral Auxiliary ◽  
Addition Reactions ◽  
Chiral Auxiliaries ◽  
Complex Molecules ◽  
Total Syntheses ◽  
Naturally Occurring ◽  
Wide Range

Background: The most frequently used chiral auxiliaries, oxazolidinones (Evans' oxazolidinones) have been employed in 1,4-congugate addition reactions to α,β-unsaturated carbonyl compounds. Supplementary to our previous reports in this mini-review, we attempted to underscore the applications of this strategy in a step (steps) in the total synthesis of some naturally occurring compounds exhibiting diverse biological activities. Objective: In this mini-review, we try to underscore the applications of oxazolidinones (Evans’ oxazolidinones) in 1,4-congugate addition reactions to α,β-unsaturated carbonyl in the total synthesis of some naturally occurring compounds exhibiting diverse biological activities. Conclusion: In spite of well-known superiority of asymmetric catalyzed reactions, the use of auxiliarycontrolled reactions are still considered as commanding, vital and sometimes as only tools in the generation of stereogenic centers during the construction of complex molecules and total synthesis of naturally occurring compounds. The commercial availability, or readily accessibility of a wide variety of chiral amino alcohols as starting materials to synthesize a wide range of oxazolidinones is the merits of them. In addition, the ease of removal and subjection to various and diverse stereoselective reactions make oxazolidinones as the ideal and superior chiral auxiliaries. In this regard, they were successfully used in asymmetric 1,4-conjugate addition reactions with high stereoselectivities. The high degree of asymmetric induction can be attributed to the rigid chelation of N-acyloxazolidinones with metal ions, as well as the covering of one face of the system by the bulkiness of 4-substituent. In summary, in this report, the importance of the applications of chiral oxazolidinones as suitable chiral auxiliaries in the stereoselective, 1,4-conjugate addition reactions in asymmetric synthesis and in particular, the total synthesis of naturally occurring compounds and some complex molecules were underscored. Noticeably, in these total syntheses, this chiral auxiliary is controlling the stereochemistry of a newly created stereogenic center as well as preserving the configuration of other chiral centers, which already have been presented in the precursor. General methods have been established for the attachment of the chiral auxiliary as a moiety to the substrate molecule in high to excellent yields. At the end of these reactions, this auxiliary can be easily removed leaving various desired reactive motifs for the next step in multi-step synthesis.

A Concise Total Synthesis of (±)-Mesembrine

Synlett ◽  
2018 ◽  
Vol 29 (09) ◽  
pp. 1203-1206 ◽  
Author(s):  
Hyoungsu Kim ◽  
Hosam Choi ◽  
Kiyoun Lee
Keyword(s):  
Total Synthesis ◽  
Claisen Rearrangement ◽  
Addition Reaction ◽  
Conjugate Addition ◽  
Allylic Oxidation ◽  
Quaternary Stereocenter

A concise total synthesis of (±)-mesembrine has been successfully accomplished in seven steps and 24% overall yield from commercially available 3-ethoxy-2-cyclohexen-1-one. Central to the assembly of the skeleton of mesembrine are a Johnson–Claisen rearrangement for the formation of the benzylic quaternary stereocenter and direct allylic oxidation to generate the substrate for the amidation/transannular aza-conjugate addition reaction.

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