69256-18-4Relevant academic research and scientific papers
Absolute configuration of aflastatin A, a specific inhibitor of aflatoxin production by Aspergillus parasiticus
Ikeda, Hiroyuki,Matsumori, Nobuaki,Ono, Makoto,Suzuki, Akinori,Isogai, Akira,Nagasawa, Hiromichi,Sakuda, Shohei
, p. 438 - 444 (2000)
Aflastatin A (1) is a specific inhibitor of aflatoxin production by Aspergillus parasiticus. It has the novel structure of a tetramic acid derivative with a long alkyl side chain. The absolute configurations of 29 chiral centers contained in I were chemically elucidated in this study. First, four small fragment molecules were prepared from I or its methyl ether (2), and their absolute structures were assigned as N-methyl-D-alanine, (2S,4R)-2,4-dimethyl-1,6-hexanediol dibenzoate, (R)-3-hydroxydodecanoic acid, and (R)-1,2,4-butanetriol tribenzoate. Next, an acyclic fragment molecule 3 with 13 chiral centers was obtained from I by NaIO4 oxidation, and its relative stereochemistry was elucidated by J-based configuration analysis. By analyzing coupling constants of 3J(H,H) and 2,3J(C,H) and ROE data, the relative configuration of 3 was verified. Finally, by further J-based configuration analysis using a fragment molecule 7 prepared from 2 with 28 chiral carbons, all relative configurations in the alkyl side chain of I were clarified. By connecting these relative configurations with the absolute configurations of first four fragment molecules, the absolute stereochemistry of 1 was fully determined.
Diastereo- and enantioselective synthesis of dimethylcyclohexanamines by asymmetric reductive amination
Speckenbach,Bisel,Frahm
, p. 1325 - 1330 (2007/10/03)
A series of optically active dimethylcyclohexanamines 6a-c, e, with ee values ranging from 86- > 99%, have been synthesised by asymmetric reductive amination of the corresponding racemic diastereomeric cyclohexanones 3a-c, e. Their conformation and configuration are also discussed.
Total Synthesis of (+/-)-Pyridoxatin
Snider, Barry B.,Lu, Qing
, p. 8065 - 8070 (2007/10/02)
An efficient two-step route to pyridoxatin analogues 13 and 15 has been developed.Condensation of 4-hydroxypyridone (4) with citronellal (10) affords o-quinone methide intermediate 11, which reacts further to give inverse electron demand Diels-Alder adducts 12 and 16 and ene adduct 14.Oxidation of 12 and 14 with MoO5 by Sammes' procedure completes the synthesis of 13 and 15.Using this approach, the first total synthesis of (+/-)-pyridoxatin (1) has been carried out in seven steps from cis-2,4-dimethylcyclohexanone (21).The key step is the condensation of 4-hydroxypyridone (4) with the allylic silane aldehyde 26 to give 35percent of cyclohexylpyridones 2 and 30.
Preparation of Optically Pure cis-2,4-Dimethyl-1-cyclohexanones, the Key Intermediates in Cycloheximide Synthesis, Using Microbial Resolution
Oritani, Takayuki,Kudo, Sachio,Yamashita, Kyohei
, p. 757 - 760 (2007/10/02)
Asymmemtric hydrolysis of acetate (10) of (+/-)-t-2,t-4-dimethyl-r-1-cyclohexanol with Bacillus subtilis var. niger gave (-)-(1S,2S,4S)-2,4-dimethyl-1-cyclohexanol (6a) and (+)-(1R,2R,4R)-acetate (10b) with high optical purities.Optically pure (-) and (+)-alcohols (6a and 6b) were prepared via corresponding 3,5-dinitrobenzoates.Oxidation of alcohols (6a and 6b) with chromic acid gave optically pure (-)-(2S,4S) and (+)-(2R,4R)-2,4-dimethyl-1-cyclohexanones (2a and 2b), respectively.
