Sulfonamide, Phenolate, and Directing Ligand-Free Indium Initiators for the Ring-Opening Polymerization ofrac-Lactide

• DOI: 10.1021/om101166s
• Publication Date: 2011-02-18T13:26:56Z
• Authors: Matthew P. Blake; Andrew D. Schwarz; Philip Mountford
• Keywords: Amide; Lactide; Sulfonamide

Reaction of In(CH2SiMe3)3 with H2N2TsNpy or H2N2TsNOMe gave the five-coordinate indium alkyls In(N2TsNpy)(CH2SiMe3) (14) and In(N2TsNOMe)(CH2SiMe3) (15). The corresponding reaction H2N2TsNPh four-coordinate In(N2TsNPh)(CH2SiMe3) (16). In{N(SiMe3)2}3 amide In(N2TsNpy){N(SiMe3)2} (19). Na2N2TsNpy InCl3 in THF followed by LiOiPr "ate" product In(N2TsNpy)(OiPr)Cl{Li(THF)} (21). chloride complex In(N2TsNpy)Cl(py) (22) was also isolated. H2O2MeNpy bis(phenolate)amine compound In(O2MeNpy)(CH2SiMe3) (23), iPrOH Me2NCH2CH2OH mixed alkyl-alkoxides In(CH2SiMe3)2(OiPr) (17) In(CH2SiMe3)2(OCH2CH2NMe2) (18), which are dimeric solid state. X-ray structures 14, 15, 17−19, 21 − 23 have been determined. compounds were evaluated as initiators for ring-opening polymerization rac-lactide. With alkyl initiators, Mn control poor because an unfavorable mismatch between initiation propagation rates. molecular weight better, but ROP slow. best-behaved initiator terms living (17). When used alone, a very initiator, presence BnNH2 amine-co-initiated immortal occurred to give atactic amine-terminated PLA controlled manner. Use Et3N place 4-fold increase activity substantial heterotacticity (Pr = 0.85). Initial studies showed that alone could produce heterotactically enriched, at room temperature, albeit slowly. (H2N2TsNpy (2-NC5H4)CH2N(CH2CH2NHTs)2; MeOCH2CH2N(CH2CH2NHTs)2; PhCH2N(CH2CH2NHTs)2; (2-NC5H4)CH2N(CH2ArOH)2 (Ar C6H2Me2).)