Preparation of Campholenal Analogues: Chirons for the lipophilic moiety of sandalwood-like odorant alcohols
作者:Christian Chapuis、Robert Brauchli
DOI:10.1002/hlca.19920750507
日期:1992.8.13
In connection with structure-activityrelationship studies, analogues of campholenal ((+)-4b), an important building block for sandalwood-like odorants, were prepared. The five-membered-ring analogues 4 were obtained by epoxidation of the corresponding α-pinene derivatives 2, followed by catalytic ZnBr2 isomerisation (Scheme 2). The six-membered-ring skeleton was obtained by ozonolysis of α-campholenyl
Boric Acid-Catalyzed Direct Condensation of Carboxylic Acids with Benzene-1,2-diamine into Benzimidazoles
作者:Nenad Maraš、Marijan Kočevar
DOI:10.1002/hlca.201100064
日期:2011.10
applicability of boric acid catalysis for the direct condensation of carboxylicacids with benzene‐1,2‐diamine to give 2‐substituted benzimidazoles was investigated. It was found that catalytic amounts (5–10 mol‐%) of boric acid efficiently promote the cyclocondensation of aliphatic carboxylicacids in refluxing toluene. In addition, the relatively neutral conditions allow the use of acid‐sensitive substrates