Publication

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

Manfred Schlosser
1998
Journal Articles

Abstract

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)]

Official source

https://infoscience.epfl.ch/entities/publication/ea9c2736-eb10-40cf-a68f-b4f25307552b

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Manfred Schlosser
1998
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/ea9c2736-eb10-40cf-a68f-b4f25307552b

About this result

Related concepts (7)

Open-chain compound

In chemistry, an open-chain compound (also spelled as open chain compound) or acyclic compound (Greek prefix "α", without and "κύκλος", cycle) is a compound with a linear structure, rather than a cyclic one. An open-chain compound having no side chains is called a straight-chain compound (also spelled as straight chain compound). Many of the simple molecules of organic chemistry, such as the alkanes and alkenes, have both linear and ring isomers, that is, both acyclic and cyclic, with the latter often classified as aromatic.

Cyclic compound

A cyclic compound (or ring compound) is a term for a compound in the field of chemistry in which one or more series of atoms in the compound is connected to form a ring. Rings may vary in size from three to many atoms, and include examples where all the atoms are carbon (i.e., are carbocycles), none of the atoms are carbon (inorganic cyclic compounds), or where both carbon and non-carbon atoms are present (heterocyclic compounds with rings containing both carbon and non-carbon).

Ring strain

In organic chemistry, ring strain is a type of instability that exists when bonds in a molecule form angles that are abnormal. Strain is most commonly discussed for small rings such as cyclopropanes and cyclobutanes, whose internal angles are substantially smaller than the idealized value of approximately 109°. Because of their high strain, the heat of combustion for these small rings is elevated. Ring strain results from a combination of angle strain, conformational strain or Pitzer strain (torsional eclipsing interactions), and transannular strain, also known as van der Waals strain or Prelog strain.