title: Novel Asymmetric Formylation of Aromatic Compounds: Enantioselective Synthesis of Formyl 7,8-Dipropyltetrathia[7]helicenes.
abstract: Asymmetric formylation of aromatic compounds is virtually unexplored. We report the synthesis and evaluation of a library including 20 new chiral formamides in the kinetic resolution of 7,8-dipropyltetrathia[7]helicene, affording the corresponding formyl- or diformylhelicenes in up to 73 % ee, making enantiopure compounds available by recrystallisation. With the N,N-disubstituted formamides used in this study, the best enantioselectivity has been achieved with R(1) =iPr, R(2) =Me, R(3) =H, R(4) =1-naphthyl or its 1-pyrenyl equivalent.
authors.affiliation: School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ (UK).
authors.forename: Julien
authors.initials: J
authors.lastname: Doulcet
authors.affiliation: School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ (UK). G.R.Stephenson@uea.ac.uk.
authors.forename: G Richard
authors.initials: GR
authors.lastname: Stephenson
keywords: asymmetric synthesis; chiral formamides; double-kinetic resolution; enantioselective formylation; kinetic resolution