Fabrication and Diverse Ring-Expansion Nanocatalysis of Functionalized Pt-Nanoparticles to a General Synthesis of Pyrrolines: A 3D-Mid-IR Study.

An unprecedented nanofabrication of functionalized Pt-NPs under mild conditions was accomplished through oxidative insertion of PtBr2 into the O-C bond of ArCH(OMe)2. TEM and SEM imaging, EELS, XPS, and ESI-MS analyses found the NPs possessing the molecular formula Br2(MeO)PtIVCH(OMe)Ph and low-dimensional spherical morphology. Ketone and amide functionality-bearing electrophilic cyclopropanes underwent ring-opening cyclization. Size-dependent catalytic activity of the NPs was investigated using stabilizers and newly introduced PhCH(OMe)2 during the synthesis of 2-pyrrolines. The organometallic-NPs were effective for cyclopropane ring-expansion using propargyl amine to 1-pyrrolines with depropargylation. Interestingly, the diverse catalytic activity of the Pt-NPs was effective for sp³C-H activated dual cyclization for the direct synthesis of fused-pyrrolo[3,2-c]pyridones. The possible reaction pathway was investigated by 3D-mid-IR-ATR, control experiments, and ESI-MS analyses. The NPs were superior in terms of simple preparation, low catalyst loading, ease of recovery, recycling, diverse catalytic activity, and outstanding ability for the general synthesis of pyrroline analogues. [ABSTRACT FROM AUTHOR]