Removal of benzyl-type protecting groups from peptides by catalytic transfer hydrogenation with formic acid

Abstract

pyrene ll-bromo-9,10,12-triol, minor isomer, 70981-82-7; 10,11-epoxy-9,12-dihydroxy-9,10,11,12-tetrahydrobenzo[e]pyrene, 70940-93-1; 10,11-epoxy-9,12-dihydroxy-9,10,11,12-tetrahydrobenzo[e]pyrene diacetate, 70982-62-6; trans-1 triphenylene tetra01 tetraacetate, 70940-94-2; trans-% triphenylene tetraol tetraacetnte, 70981-83-8; cis-2 triphenylene tetraol tetraacetate, 70981-84-9; trar s-l benio [e]pyrene tetraol tetraacetate, 70940-95-3; cis-1 benzo[e]p~rene tetraol tetraacetate, 70981-85-0; trans-2 benzo[e]pyrene tetraol tetraacetate, 70981-86-1; cis-2 benzo[e]pyrene tetraol tetraacetate, 70981-87-2 Supplementary Material Available: Details on the hydrolysis of the Senzo[ejpyrene and triphenylene diol epoxides to tetraols and their 'H NMR spectra as tetraacetates, and the reaction of b~nzo[e]pyrene 9,lO-dihydrodiol with N-bromoacetamide as well as the cyclization of the resultant bromo triols (4 pages). Ordering information is given on any current masthead page. ~~ (16) A.Summary: a$-Acetylenic sulfones react with organolithium and Grignard reagents to give a higher acetylene and a sulfinate salt. The process corresponds to nucleophilic substitution by the organometallic for the arylsulfonyl group.

A non-tetradecarboxylative synthesis of 2,7,12,17-tetraphenylporphycene

“…12a satisfies our initial design, bearing two different ester groups at C3 and C5. In order to selectively deprotect the benzyl ester group we carried out a hydrogenolysis using 10% Pd/C as catalyst and a mixture of formic acid and ammonium formate as the hydrogen source [16]. Thus, the dicarboxylic acid 18 was obtained in quantitative yield.…”

Catalytic Transfer Hydrogenation of Bifunctional Poly(ethylene glycol) Derivatives Using Palladium−Poly(ethylenimine) Catalyst

“…These results compared favorably with literature reports where Pd-PEI has been used to remove the same type of protective group from small peptides and amino acids. 6 The great activity of Pd-PEI catalyst compared to Pdblack could be possibly due to the distribution of Pd on the large surface area available with PEI. The high rate has been also explained in terms of the possible attraction of the formic acid to the PEI matrix.…”

Anilines Made Easily: From Aldehydes to Tri‐, Tetra‐, and Pentasubstituted Anilines in Two Steps

“…In the presence of stronger hydrogen donors (H 2 , [16] HCO 2 H [17] ), saturated cyclohexane 4 a was formed in moderate yield. A significant increase in the yield of aniline 2 a was observed when triglyme was employed as the solvent and the reaction was conducted at higher temperatures.…”