Production of novel isoquinoline-containing functional reagents and new developmet

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We reported a novel and chemoselective tert-butoxycarbonylation reagent, 1-tert-butoxy-2-tert-butoxycarbonyl-1, 2-dihydroisoquinoline (BBDI), which was easily prepared in quantitative yield by the reaction of isoquinoline with Boc_2O. BBDI effected easily the tert-butoxycarbonylation for acidic substrates in the absence of bases rather than basic ones, while that for acidic compounds such as phenols, carboxylic acids using Boc_2O required some base. The synthesis of carboxylic esters is one of the most fundamental and pivotal protocols for producing natural and synthetically useful compounds in organic chemistry. The coupling reactions between activated derivatives of carboxylic acids and alcohols have been employed. These procedures are of considerable interest, especially as relate to the manipulation of peptides or complicated biologically active compounds such as macrolides. A simple and mild esterification of N-protected amino acids using BBDI as a novel condensing reagent in a on … More e-pot method was developed. This protocol has several advantages including the use of nearly equimolar amounts of alcohols, no requirement for additives, and no racemization occurs. Next, we developed a novel BBDI-catalyzed esterification of N-protected amino acids in the presence of Boc_2O under simple and mild conditions. Although a variety of methods for acid-catalyzed esterification reactions have been reported, the use of a nearly neutral catalyst such as BBDI has not been extensively investigated. Further, it was found that catalytic esterification using BBDI typed reagent derived from electron-rich isoquinoline such as 6-methoxyisoquinoline shortened a reaction time. The synthesis of carboxylic amide is one of the most fundamental and pivotal protocols for producing natural and synthetically useful compounds such as peptides in organic chemistry. We succeeded a simple and mild amidation that uses nearly equimolar amounts of a variety of carboxylic acids and amines and BBDI without the need for any additives. Less