page_title: Chiral auxiliary
section_title: trans-2-Phenylcyclohexanol
hierarchical_section_title: Chiral auxiliary / trans-2-Phenylcyclohexanol
caption_attribution_description: English: (1R,2S)-2-phenylcyclohexanol�
context_page_description: A chiral auxiliary is a stereogenic group or unit that is temporarily incorporated into an organic compound in order to control the stereochemical outcome of the synthesis. The chirality present in the auxiliary can bias the stereoselectivity of one or more subsequent reactions. The auxiliary can then be typically recovered for future use.
  General scheme for employing a chiral auxiliary in asymmetric synthesis
  Most biological molecules and pharmaceutical targets exist as one of two possible enantiomers; consequently, chemical syntheses of natural products and pharmaceutical agents are frequently designed to obtain the target in enantiomerically pure form. Chiral auxiliaries are one of many strategies available to synthetic chemists to selectively produce the desired stereoisomer of a given compound.
  Chiral auxiliaries were introduced by Elias James Corey in 1975 with chiral 8-phenylmenthol and by Barry Trost in 1980 with chiral mandelic acid. The menthol compound is difficult to prepare and as an alternative trans-2-phenyl-1-cyclohexanol was introduced by J. K. Whitesell in 1985.
context_section_description: One type of chiral auxiliary is based on the trans-2-phenylcyclohexanol motif as introduced by James K. Whitesell and coworkers in 1985. This chiral auxiliary was used in ene reactions of the derived ester of glyoxylic acid.
  In the total synthesis of (−)-heptemerone B and (−)-guanacastepene E, attached with trans-2-phenylcyclohexanol, the glyoxylate reacted with 2,4-dimethyl-pent-2-ene, in the presence of tin(IV) chloride, yielding the desired anti adduct as the major product, together with a small amount of its syn isomer with 10:1 diastereomeric ratio.
  For even greater conformational control, switching from a phenyl to a trityl group gives trans-2-tritylcyclohexanol (TTC). In 2015, the Brown group published an efficient chiral permanganate-mediated oxidative cyclization with TTC.
caption: Trans-2-phenylcyclohexanol
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