Kumada-Corriu coupling in synthesis of PAHs
Abstract
The thesis explores the Kumada-Corriu coupling reaction as a possible handle to further functionalize PAHs. The starting material used was different types of triflate bearing PAHs.An attempt at preparing phenanthren-9-yl trifluoromethanesulfonate as starting material failed. The compound was attempted synthesised using a DoM/DreM approach. The preparation of naphthalen-2-yl trifluoromethanesulfonate (5b) and chrysen-3-yl trifluoromethanesulfonate (6c) from naphthalen-2-ol (5a) and chrysen-3-ol (6b) was a success. The synthesised triflates were reacted with ethylmagnesium bromide (14), vinylmagnesium bromide (15), isopropylmagnesium chloride lithium chloride complex solution (16) and benzylmagnesium bromide (10a) using different catalysators. Yields are given in figure 1. The Ni(dppp)Cl2 catalysator (general procedure A) gave good yields with both Grignard reagent 14 and 16. Ni(dppe)Cl2 (general procedure B) and Pd(dppf)Cl2 (general procedure D) were somewhat suitable catalysators when reacting with Grignard reagent 15, but in most attempts 2-vinylnaphthalene (5d) was lost during workup. A sustainable Fe(acac)3 catalyst (general procedure C) was also used to couple the majority of the Grignard reagents with triflate 5b and 6c. The iron catalyst did not seem suitable for the reaction of alkenyl Grignard reagents, nor the self-generated benzylmagnesium bromide (10a).Further investigation could lead to a successful procedure for the coupling of styrylmagnesium bromide, made from (2-bromovinyl)benzene, whose product can be further cyclised to expand the skeletal structure of PAHs.