- A short asymmetric synthesis of (-)-neonepetalactone
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(4S.,4aR)-Neonepetalactone (6) was synthesized in high diastereomeric and enantiomeric purity (de, ee ≥ 96 %) in a four step procedure. Key step of the total synthesis is the Michael addition of metalated propanal SAMP-hydrazone ((S)-1) to 2-cyclopentenecarboxylate (2).
- Enders, Dieter,Kaiser, Anja
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p. 631 - 635
(2007/10/03)
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- Extracyclic Stereocontrol in Addition Reaction of Crotylsilanes with 2-Substituted 2-Cyclopentenones. Stereodivergent Synthesis of (+)-Neonepetalacton and (+)-Isoneonepetalactone
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The addition reaction of E- and Z-crotylsilanes with 2-substituted 2-cyclopentenones showed the preference of erythro and threo products respectively.The refinement of the selectivity was investigated and the result was utilized for efficient syntheses of
- Pan, Li-Rui,Tokoroyama, Takashi
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p. 1999 - 2002
(2007/10/02)
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- Reaction of Organoaluminium Reagents with Cyclopropylmethyl Acetates and 2-Vinylcyclopropane-1,1-dicarboxylate Esters
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Ring-opening alkylation of cyclopropylmethyl acetates was studied.The acetoxyl group of 7-(1-acetoxyheptyl)norcarane is substituted by the alkyl group upon treatment with trialkylaluminium, but alkylation of trans-1-(1-acetoxyethyl)-2-phenylcyclopropane with trialkylaluminium gives rise to trans-5-phenyl-2-alkenes.The reaction of (1S,2S)-2-phenylcyclopropylmethyl acetate with trimethylaluminium resulted in the complete loss of optical activity to give racemic 4-phenyl-1-pentene.Alkylation of trans-1-(1-acetoxy-3-phenylpropyl)-2-vinylcyclopropane with trialkylaluminium proceeds under regioselective ring-opening to give 3-alkylated trans-8-phenyl-1,5-octadiene (selectivity 73-83percent).The regio- and stereochemistry of homoconjugate addition to activated vinylcyclopropanes having a doubly carbonyl substituted ring carbon was studied.Trialkylaluminium on addition to diethyl 2-vinylcyclopropane-1,1-dicarboxylate in a 1,5-manner afford diethyl (2-alkyl-3-butenyl)propanedioate (over 96percent selectivity).In contrast, the reaction of this cyclopropane with tetraalkylaluminiumlithium takes place in a 1.7-manner to give diethyl (trans-4-alkyl-2-butenyl)propanedioate with 88-92percent selectivity.Clean regiocontrol of the reaction is observed in the methylation of ethyl exo-6-(trans-1-propenyl)-2-oxobicyclo(3.1.0>hexane-1-carboxylate with trimethylaluminium or tetramethyl aluminiumlithium.Alkylation with trimethylaluminium proceeds with 86percent inversion of the configuration at C(6) of the substrate, affording (2R*,3R*)-2-ethoxycarbonyl-3-cyclopentanone which is transformed into neonepetalactone.
- Hiyama, Tamejiro,Morizawa, Yoshitomi,Yamamoto, Hajime,Nozaki, Hitosi
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p. 2151 - 2160
(2007/10/02)
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- REVISIONS OF THE ABSOLUTE CONFIGURATIONS OF C-8 METHYL GROUPS IN DEHYDROIRIDODIOL, NEONEPETALACTONE, AND MATATABIETHER FROM ACTINIDIA POLYGAMA MIQ
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The absolute configurations of C-8 Me groups in dehydro-iridodiol, neonepetalactone, and matatabiether isolated from the cat- and lacewing-attracting plant Actinidia polygama Miq. were revised to the S configurations on the basis of chemical transformatio
- Sakai, Tsutomu,Nakajima, Kimiko,Yoshihara, Kazuo,Sakan, Takeo,Isoe, Sachihiko
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p. 3115 - 3119
(2007/10/02)
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