Strained rings to assess the "endo preference" of 2-alkyl branched 2-alkenylpotassium species

Upon deprotonation using trimethylsilylmethylpotassium or butyllithium in the presence of potassium tert-butoxide, two allylic organopotassium species are generated from the (E)-isomeric caryophyllene and the (Z)-isomeric isocaryophyllene. Torsional equilibration occurs slowly at -50 DegC (in THF) and rapidly at 0 DegC (in hexane) to afford endo/exo-mixts. of about 95:5 (as evidenced by the isomeric compn. of the trapping products). The relative thermodn. stabilities of the two stereoisomeric organometallic intermediates can be derived by mere superposition of ring-strain differences and the \"endo preference\" of open-chain (alkylalkenyl)potassium compds. [on SciFinder (R)]


Published in:
Tetrahedron Letters, 39, 23, 4031-4034
Year:
1998
Keywords:
Note:
CAN 128:321324
22-7
Physical Organic Chemistry
Institut de Chimie organique de l'Universite,Lausanne-Dorigny,Switz.
Journal
0040-4039
written in English.
78683-81-5P; 79768-25-5P Role: SPN (Synthetic preparation), PREP (Preparation) (prepn. of); 87-44-5 (Caryophyllene); 118-65-0 (Isocaryophyllene) Role: RCT (Reactant), RACT (Reactant or reagent) (ring strain in metalation, borylation and oxidn. of caryophyllene and isocaryophyllene)
Laboratories:




 Record created 2006-03-03, last modified 2018-01-27


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