Concise Synthesis of the ABC-Ring System of the Azafluoranthene, Tropoisoquinoline and Proaporphine Alkaloids: An Olefin Hydroacylation/Pomeranz–Fritsch Cyclization Approach

Synthesis ◽  
2019 ◽  
Vol 51 (09) ◽  
pp. 2030-2038 ◽  
Author(s):  
Didier Vargas ◽  
Enrique Larghi ◽  
Teodoro Kaufman
Keyword(s):  
Reductive Amination ◽  
Claisen Rearrangement ◽  
Ring System ◽  
System Characteristic ◽  
Synthetic Sequence ◽  
Ac Ring ◽  
Straightforward Approach

A straightforward approach toward a decorated cyclopenta[ij]isoquinoline embodying the ABC-ring system characteristic of the azafluoranthene (triclisine), tropoisoquinoline (pareitropone) and proaporphine (prodensiflorin B) alkaloids, is reported. The synthetic ­sequence entailed a novel 40% KF/Al2O3-mediated hydroacylation of a 2-allyl-benzaldehyde derivative, obtained in two steps from isovanillin, through O-allylation and Claisen rearrangement to assemble the AC-ring system. This was followed by an O-methylation and a reductive ­amination of the resulting indanone with aminoacetal. A modified Pomeranz–Fritsch cyclization was next implemented to install ring B, through sulfonamidation, followed by acid-promoted cyclization and ­final desulfonylation in situ.

scholarly journals One-Pot Synthesis of Novel Multisubstituted 1-Alkoxyindoles

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1466
Author(s):  
Ye Eun Kim ◽  
Hyunsung Cho ◽  
Yoo Jin Lim ◽  
Chorong Kim ◽  
Sang Hyup Lee
Keyword(s):  
Alkyl Halide ◽  
The Novel ◽  
Reaction Conditions ◽  
One Pot ◽  
One Pot Synthesis ◽  
Consecutive Reactions ◽  
Intramolecular Condensation ◽  
Synthetic Sequence ◽  
Novel Target

Studies on a one-pot synthesis of novel multisubstituted 1-alkoxyindoles 1 and their mechanistic investigations are presented. The synthesis of 1 was successfully achieved through consecutive four step reactions from substrates 2. The substrates 2, prepared through a two-step synthetic sequence, underwent three consecutive reactions of nitro reduction, intramolecular condensation, and nucleophilic 1,5-addition to provide the intermediates, 1-hydroxyindoles 8, which then were alkylated in situ with alkyl halide to afford the novel target products 1. We optimized the reaction conditions for 1 focusing on the alkylation step, along with the consideration of formation of intermediates 8. The optimized condition was SnCl2·2H2O (3.3 eq) and alcohols (R1OH, 2.0 eq) for 1–2 h at 40 °C and then, base (10 eq) and alkyl halides (R2Y, 2.0 eq) for 1–4 h at 25–50 °C. Notably, all four step reactions were performed in one-pot to give 1 in good to modest yields. Furthermore, the mechanistic aspects were also discussed regarding the reaction pathways and the formation of side products. The significance lies in development of efficient one-pot reactions and in generation of new 1-alkoxyindoles.

A new route to the cis–anti–cis triquinane ring system. The synthesis of 4,4-dimethyltricyclo[6.3.0.02,6]undecan-3-one via β-enolate rearrangement

1984 ◽  
Vol 62 (10) ◽  
pp. 1926-1929 ◽  
Author(s):  
Hemant A. Patel ◽  
J. B. Stothers
Keyword(s):  
Ring System ◽  
System Characteristic

A synthesis of cis, anti, cis-4,4-dimethyltricyclo[6.3.0.026]undecan-3-one is described in which the key step is β-enolate rearrangement of 9,9-dimethyltricyclo[5.3.1.01.5]undecan-10-one proceeding with retention of configuration. The required [5.3.1.01.5] ketone was prepared in six steps from tricyclo[5.2.1.01.5]dec-8-ene. This sequence constitutes a new route to the tricyclo[6.3.0.02.6]undecane ring system characteristic of the hirsutane sesquiterpenes. The 13C data for several tricyclic derivatives are reported.

ChemInform Abstract: Synthesis of 1,2-Dihydro-2-allylindol-3-ones Using in situ Claisen Rearrangement of 1,2-Dihydroindol-3-ones with Allyl Alcohols

ChemInform ◽  
2010 ◽  
Vol 26 (18) ◽  
pp. no-no
Author(s):  
T. KAWASAKI ◽  
K. MASUDA ◽  
Y. BABA ◽  
K. TAKADA ◽  
M. SAKAMOTO
Keyword(s):  
Claisen Rearrangement ◽  
Allyl Alcohols

Access to the Naproxen Ring System, a Crowded β‐Lactam, through In Situ Generated Ketenes: Synthesis, Molecular Docking, and Evaluation of Anticonvulsant Activity

2020 ◽  
Vol 5 (44) ◽  
pp. 14190-14197
Author(s):  
Somayeh Salarinejad ◽  
Mohammad Reza Islami ◽  
Mehdi Abbasnejad ◽  
Fatemeh Zigheimat ◽  
Razieh Kooshki ◽  
...  
Keyword(s):  
Molecular Docking ◽  
Anticonvulsant Activity ◽  
Ring System ◽  
System A

Intramolecular Michael Addition of N- and O-Centred Nucleophiles to Tethered Acrylates. The Role of Double-Bond Geometry in Controlling the Diastereo- selectivity of Cyclizations Leading to 2,6-Disubstituted Tetrahydropyrans and Piperidines.

1998 ◽  
Vol 51 (1) ◽  
pp. 9 ◽  
Author(s):  
Martin G. Banwell ◽  
Brett D. Bissett ◽  
Chinh T. Bui ◽  
Ha T. T. Pham ◽  
Gregory W. Simpson
Keyword(s):  
Double Bond ◽  
Total Synthesis ◽  
Michael Addition ◽  
Reductive Amination ◽  
Major Product ◽  
Enantioselective Synthesis ◽  
Cyclization Reactions ◽  
Glandular Secretion

The oxyanion derived from hydroxyacrylate E-(5) undergoes smooth intramolecular Michael addition to give the trans-2,6-disubstituted tetrahydropyran (7) as the major product of reaction. In contrast, the oxyanion obtained from isomer Z-(5) cyclizes to give the cis-2,6-disubstituted tetrahydropyran (6) as the major product. Such chemistry has been extended to the enantioselective synthesis of (+)-(6) the acquisition of which constitutes a formal total synthesis of acid (+)-(2), a constituent of the glandular secretion from the civet cat (Viverra civetta). Reductive amination of keto acrylate (12) affords an intermediate amine which cyclizes, in situ, to give the cis-2,6-disubstituted piperidine (26). Analogous treatment of compound (13) delivers the isomeric trans-2,6-disubstituted piperidine (27) as the exclusive product of reaction. Transition state structures have been proposed to account for the diastereoselectivities observed in all of the cyclization reactions.

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