A new general synthetic route to bridged carboxylic ortho esters

✍ Scribed by E.J. Corey; Natarajan Raju

• Publisher: Elsevier Science
• Year: 1983
• Tongue: French
• Weight: 216 KB
• Volume: 24
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)94143-1

✦ Synopsis

Acylation of the readily available 3-methyl-3-hydroxymethyl oxetane Q leads to the corresponding oxetane esters (3 which rearrange smoothly in the presence of boron trifluoride etherate in methylene chloride at -15" to form ortho esters of the 2,6,7-trioxabicyclo[2.2. aloctane series (2).

Protection of the carboxylic acid function as an ortho ester derivative is a valuable tactic of synthetic practice, in part because of the stability of the ortho ester unit toward strongly basic reagents and the ease of carboxylic acid regeneration under mildly acidic conditions. Bridged ortho esters derived from 2,2-bishydroxymethyl-1-propanol (I_) are especially useful because of their chromatographic stability as compared to acyclic ortho esters. I,2 We describe herein a new and practical synthetic route to bridged ortho esters from carboxylic acids. Previously ortho esters have been prepared