Reagent-free continuous thermal tert-butyl ester deprotection

Enhancing the Delamination Efficiency of Polyimide-Copper Bilayers with UV/Heat-Activated Foamable Adhesive: Insights and Applications

This study explores the adhesive properties of copolymers comprising glycidyl methacrylate (GMA) and 3-(trimethoxysilyl)propyl methacrylate (MPTMS), focusing on their suitability for adhesive applications. Peel resistance measurements revealed a substantial impact of the GMA/MPTMS ratio on adhesion capabilities, identifying an optimal ratio of 30/70 for copolymerization with tert-butyl acrylate (tBA) to improve foaming performance. tBA, a foaming monomer activated by a photoacid generator and heat, enhances the copolymerized adhesive's adhesion strength and foamability for postuse delamination. Chemical structure analysis through Nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR) confirmed successful polymerization, while rheological properties indicated decreased complex viscosity and adhesive strength with an increasing tBA content. The deprotection of the t-butyl group facilitated foam formation, supported by morphology analysis. These findings provide insights into foamable adhesive development with potential applications in delamination processes and implications for further exploration in polymer adhesion.

Triarylamminium Radical Cation Facilitates the Deprotection of tert-Butyl Groups in Esters, Ethers, Carbonates, and Carbamates

We report a catalytic protocol for mild OtBu deprotection using two commercial reagents: the tris-4-bromophenylamminium radical cation, commonly known as magic blue (MB^•+), and triethylsilane. Magic blue catalytically facilitates the cleavage of the C-O bond in tert-butyl carbamates, carbonates, esters, and ethers in a high isolated yield of up to 95%, and sacrificial triethylsilane accelerates the reaction. Without requiring high temperatures, transition metals, or strong acidic or basic catalysts, this method is suitable for structurally diverse compounds, including aliphatic, aromatic, and heterocyclic substrates.

Deprotection of N-Boc Groups under Continuous-Flow High-Temperature Conditions

The scope of thermolytic, N-Boc deprotection was studied on 26 compounds from the Pfizer compound library, representing a diverse set of structural moieties. Among these compounds, 12 substrates resulted in clean (≥95% product) deprotection, and an additional three compounds gave ≥90% product. The thermal de-Boc conditions were found to be compatible with a large number of functional groups. A combination of computational modeling, statistical analysis, and kinetic model fitting was used to support an initial, slow, and concerted proton transfer with release of isobutylene, followed by a rapid decarboxylation. A strong correlation was found to exist between the electrophilicity of the N-Boc carbonyl group and the reaction rate.