10.1021/op300162d
The research focuses on the optimization of the reductive debenzylation of hexabenzylhexaazaisowurtzitane (HBIW), a key step in the synthesis of high energy density material HNIW (CL-20). The study employs palladium hydroxide on activated carbon as a catalyst, characterized using techniques like nitrogen adsorption/desorption isotherm, hydrogen isotherm, SEM, and TEM. A central composite design (CCD) was utilized to optimize reaction conditions, examining the impact of four variables: catalyst to HBIW percent, reaction temperature, hydrogen pressure, and acetic anhydride (Ac2O) mole ratio on reaction yield. The optimal conditions were determined to be 20% (w/w) catalyst to HBIW, 48.5°C reaction temperature, 4.25 bar hydrogen pressure, and an Ac2O/HBIW mole ratio of 10.9, resulting in a 73% yield. The experiments involved the use of HBIW, DMF, acetic anhydride, and bromobenzene, with the synthesized product TADB characterized by melting point and TLC. The catalyst was analyzed for surface area, pore size distribution, active surface area, and palladium distribution using the aforementioned techniques.
10.1055/s-0030-1260232
The study presents an innovative one-pot synthetic method involving sequential isomerization, Wittig olefination, and hydrogenation of primary allylic alcohols. The process begins with the isomerization of allylic alcohols to aldehydes using Pd(OH)2 as the catalyst. Subsequently, stabilized Wittig ylides are added to the reaction mixture to perform the olefination, converting the aldehydes into α,β-unsaturated carbonyl derivatives. In the final step, additional Pd(OH)2 catalyst is introduced, and the reaction mixture is subjected to hydrogenation, resulting in the formation of saturated carbonyl derivatives. The study also explores a variation of this process involving an oxa-Michael addition reaction, yielding tetrahydropyran derivatives with high diastereoselectivity. This method offers an efficient and environmentally favorable approach to synthesizing complex organic molecules from simple allylic alcohols, with potential applications in the synthesis of pharmaceuticals, agrochemicals, and other fine chemicals.
10.1016/j.tet.2018.04.082
The study presents a simplified method for beta-glycosylation of peptides, focusing on the activation of S-phenyl thioglycosides using N-iodosuccinimide and catalytic copper(I) triflate. This method effectively promotes beta-O-glycosylation at serine and threonine hydroxyls in "mono-," di-, and tripeptides, as well as beta-N-glycosylation of asparagine-containing peptides. A key advantage is the minimization of undesired amide O-glycosylation. The study also develops streamlined deprotection sequences based on global hydrogenolysis, leading to the parent glycopeptides. The core glycopeptide region for biological protein N-glycosylation has been synthesized, purified, and characterized. The research provides an efficient process for O- and N-glycosylation of peptides, which is beneficial for multistep preparations, especially those limited by material availability.
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