126348-20-7Relevant articles and documents
Preparation of Some Chromans Substituted at the 3- or 4-Position by an Aryl or Benzyl Group, by the Rhodium-catalysed Intramolecular Nucleophilic Substitution of the Corresponding 3-(2-Fluorophenyl)propanols
Houghton, Roy P.,Shervington, Leroy A.
, p. 1872 - 1892 (2007/10/02)
The bis(hexafluorophosphate) salt of the (η5-ethyltetramethylcyclopentadienyl)(η6-benzene)rhodium(III) cation has been used as a catalyst to prepare 3-phenyl-, 3-(4-methoxyphenyl)-, 3-(4-nitrophenyl)-, and 4-benzylchroman by cyclisation of the corresponding substituted 3-(2-fluorophenyl)-propanols in nitromethane-acetone solution. 3-Phenyl-4-hydroxymethylchroman and 3-hydroxymethyl-4-phenylchroman were prepared similarly.An attempt to prepare a bis(chroman) by a double cyclisation with 2-propane-1,3-diol afforded only the monochroman, 4-(2-fluorophenyl)-3-hydroxymethylchroman.Under the conditions of the cyclisation, the erythro and threo forms of 1,4-di(2-fluorophenyl)-butane-2,3-diol afforded only the corresponding 1,3-dioxolanes as the result of the diols reacting with the acetone used as cosolvent.The 1H n.m.r. spectra of the 3-substituted and 3,4-disubstituted chromans which have been prepared are consistent with the heterocyclic ring being in the half-chair conformation (6).
