En Route to the Total Synthesis of Tashironin: The Exercise of Stereochemical Control by a Methyl Group in Mediating Remote Cyclization Reactions.

ChemInform ◽  
2005 ◽  
Vol 36 (22) ◽  
Author(s):  
Silas P. Cook ◽  
Christoph Gaul ◽  
Samuel J. Danishefsky
Keyword(s):  
Total Synthesis ◽  
Cyclization Reactions ◽  
Methyl Group ◽  
Stereochemical Control

scholarly journals Stereoselective total syntheses of (±)-sinularene and (±)-5-epi-sinularene: a general intramolecular Diels–Alder approach to tricyclic sesquiterpenes

1985 ◽  
Vol 63 (4) ◽  
pp. 993-995 ◽  
Author(s):  
Kazimierz Antczak ◽  
John F. Kingston ◽  
Alex G. Fallis
Keyword(s):  
Double Bond ◽  
Methyl Ester ◽  
Total Synthesis ◽  
Ring System ◽  
Diels Alder ◽  
Exocyclic Double Bond ◽  
Total Syntheses ◽  
Methyl Group ◽  
Secondary Hydroxyl ◽  
Selective Hydrogenolysis

Stereoselective total synthesis of (±)-sinularene and (±)-5-epi-sinularene are described. The sequence employs a "blocked" cyclopentadiene in which the cyclopropane unit also serves as a latent methyl group. Thus intramolecular [4 + 2] cycloaddition of the substituted methyl spiro[2.4]hepta-4,6-dien-1-yl)-2-pentenoate 11 affords 5-benzyloxy-6-isopropyl-8-carbomethoxytetracyclo[5.4.01,7.02,4.02,9]undec-10-ene (12) which after selective hydrogenolysis generates the tricyclo[4.4.01,6.02,8]decane (sinularene) ring system. Removal of the secondary hydroxyl function (Ph3P/CCl4/CH3CN; H2/Pd/C), reduction of the methyl ester (LiAlH4), and introduction of the exocyclic double bond (acetate pyrolysis, 550 °C) completes the synthesis of (±)-sinularene in 14 steps from cyclopentadiene. A parallel series of reactions employing the isopropyl epimer of 12 affords (±)-5-epi-sinularene.

scholarly journals New cyclization reactions in organic syntheses

2002 ◽  
Vol 74 (1) ◽  
pp. 159-166 ◽  
Author(s):  
Iwao Ojima
Keyword(s):  
Amino Acids ◽  
Transition Metal ◽  
Total Synthesis ◽  
Cyclization Reactions ◽  
Organic Syntheses ◽  
Carbocyclic Compounds ◽  
Efficient Construction ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

Recent development in the transition metal-catalyzed cyclization reactions for organic syntheses in the author's laboratories is summarized, which includes (i) novel silylcarbocyclizations (SiCaCs) and carbonylative carbotricyclizations, (ii) intramolecular silylformylations and desymmerization of siloxydiynes by sequential double silylformylation, (iii) efficient total synthesis of (+)-prosopinine, (iv) enantioselective desymmetrization of aminodienes, and (iv) new and efficient routes to 1-azabicyclo[x.y.0]alkane amino acids. All these processes are catalyzed by Rh or Rh­Co complexes, and useful for rapid and efficient construction of a variety of heterocyclic and carbocyclic compounds. Mechanisms of these new carbocyclization and cyclohydrocarbonylation reactions are also discussed.

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.

ChemInform Abstract: Oxidation Cyclization Reactions of Trienes and Dienynes: Total Synthesis of Membrarollin (I).

ChemInform ◽  
2009 ◽  
Vol 40 (23) ◽  
Author(s):  
Claire L. Morris ◽  
Yulai Hu ◽  
Geoff D. Head ◽  
Lynda J. Brown ◽  
William G. Whittingham ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Cyclization Reactions

Total synthesis and biological evaluation of oscillatoxin D, E, and F

2021 ◽  
Author(s):  
Yusuke Araki ◽  
Yusuke Hanaki ◽  
Masaki Kita ◽  
Koutaro Hayakawa ◽  
Kazuhiro Irie ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Cell Line ◽  
Biological Activities ◽  
Biological Evaluation ◽  
Marine Cyanobacteria ◽  
Methyl Group ◽  
Synthetic Strategy ◽  
Target Molecules ◽  
Synthesis And Biological Evaluation

Abstract Oscillatoxins (OTXs) and aplysiatoxins (ATXs) are biosynthetically related polyketides produced by marine cyanobacteria. We previously developed a synthetic route to phenolic O-methyl analogs of OTX-D and 30-methyl-OTX-D during collective synthesis of these natural products. According to our synthetic strategy, we achieved total synthesis of OTX-D, 30-methyl-OTX-D, OTX-E, and OTX-F by deprotecting the O-methyl group in an earlier intermediate, and determined their biological activities. Although OTX-D and 30-methyl-OTX-D have been reported to show anti-leukemic activity against L1210 cell line, we found that their cytotoxicity in vitro against this cell line is relatively weak (IC50: 29–52 μM). In contrast, OTX-F demonstrated cell line-selective anti-proliferative activity against DMS-114 lung cancer cells, which implies that OTXs target as yet unknown target molecules as part of this unique activity.

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