Synthesis of trimethoxy- or triethoxysilane-endcapped polylactones via a bismuth(III)hexanoate-catalyzed one-pot-procedure

It was shown that bismuth(III)hexanoate (Bi(OHeX)(3)) efficiently and selectively catalyzes the addition of tetra(ethylene glycol) (TEG) onto the isocyanate group of 3-isocyanatopropyl triethoxysilane, IPTES. delta-Valerolactone (delta VL), E-caprolactone (epsilon CL) and D,L-lactide were polymerized by initiation with TEG/Bi(OHex)(3). The resulting telechelic polyesters were in situ functionalized with IPTES or with 3-isocyanatopropyl trimethoxysilane, IPTMS. Using pentaerythritol as co-initiator of Bi(OHex)3 and eCL as monomer, star-shaped polylactones having triethylsilyl end-groups were synthesized in a one-pot-procedure. All functionalized polyesters were characterized by H-1-NMR and C-13-NMR spectroscopy and by MALDI-TOF mass spectrometry. Bi(OHex)(3) is a remarkable initiator and catalyst, because of its extraordinary low toxicity.