反应详情

A synthetic pathway to compounds of the invention is depicted in scheme 1. Protected HEAA derivatives 3 and 10 were prepared respectively starting from 2-(tetrahydro-2H-pyran-2-yloxy)ethanol 1 (commercially available or obtained from THP selective monoprotection of diethylene glycol) and commercially available 2-(benzyloxy)ethanol 8. Fully protected 3 was obtained by a two steps procedure including formation of acid 2 by reaction of alcohol 1 with bromoacetic acid, followed by DIC/DMAP promoted coupling with benzyl alcohol. Further removal of THP protecting group afforded alcohol 4 which was coupled with acid 2 to give dimer 5 with 82% yield. Final deprotection by acidic treatment led to the obtention of desired alcohol 6, first building block for key trimer compound 11 obtention. This conversion also led to the formation of small amounts of alcohol 7, thus reflecting the instability of this latter in these conditions (probable intramolecular transesterification of the dimer alcohol 6). Attempts to obtain pure dimer 6 by flash chromatography gave only poor yields and crude residue was finally used for next step without further purification.

1. customwere prepared respectively