328381-75-5Relevant academic research and scientific papers
Total synthesis and structural confirmation of brevisamide, a new marine cyclic ether alkaloid from the dinoflagellate Karenia brevis
Kuranaga, Takefumi,Shirai, Tomohiro,Baden, Daniel G.,Wright, Jeffrey L. C.,Satake, Masayuki,Tachibana, Kazuo
scheme or table, p. 217 - 220 (2009/06/20)
The first total synthesis of brevisamide (1) has been accomplished in 21 linear steps starting from cis-but-2-ene-1,4-diol. A synthetic highlight is the Suzuki-Miyaura coupling between an ether ring fragment and a dienol side chain. This result confirmed the structure of 1 isolated from the dinoflagellate Karenia brevis.
Stereochemistry of Nucleophilic Substitution Reactions Depending upon Substituent: Evidence for Electrostatic Stabilization of Pseudoaxial Conformers of Oxocarbenium Ions by Heteroatom Substituents
Ayala, Leticia,Lucero, Claudia G.,Antoinette, Jan,Romero,Tabacco, Sarah A.,Woerpel
, p. 15521 - 15528 (2007/10/03)
Lewis acid-mediated nucleophilic substitution reactions of substituted tetrahydropyran acetates reveal that the conformational preferences of six-membered-ring cations depend significantly upon the electronic nature of the substituent. Nucleophilic substitutions of C-3 and C-4 alkyl-substituted tetrahydropyran acetates proceeded via pseudoequatorially substituted oxocarbenium ions, as would be expected by consideration of steric effects. Substitutions of C-3 and C-4 alkoxy-substituted tetrahydropyran acetates, however, proceeded via pseudoaxially oriented oxocarbenium ions. The unusual selectivities controlled by the alkoxy groups were demonstrated for a range of other heteroatom substituents, including nitrogen, fluorine, chlorine, and bromine. It is believed that the pseudoaxial conformation is preferred in the ground state of the cation because of an electrostatic attraction between the cationic carbon center of the oxocarbenium ion and the heteroatom substituent. This analysis is supported by the observation that selectivity diminishes down the halogen series, which is inconsistent with electron donation as might be expected during anchimeric assistance. The C-2 heteroatom-substituted systems gave moderately high 1,2-cis selectivity, while small alkyl substituents showed no selectivity. Only in the case of the tert-butyl group at C-2 was high 1,2-trans selectivity observed. These studies reinforce the idea that ground-state conformational effects need to be considered along with steric approach considerations.
Total synthesis of lankacyclinol
Williams, David R.,Cortez, Guillermo S.,Bogen, Stephane L.,Rojas, Christian M.
, p. 4612 - 4615 (2007/10/03)
An antitumor agent from various Streptomyces species, the title compound 1, has been synthesized for the first time, as described here. Key steps involved include a ring-closing metathesis, a photochemically induced acylnitrene insertion process, and high
