Dear Suresh,

many thanks for sharing this very interesting chemical question with the RG community. A well-establshed and highly useful protecting group for primary alcohols is the tert-butyldimethylsilyl group (TBDMS). It is easily introduced by treatment of the alcohol precursor (in your case losartan) with TBDMSCl in the presence of a base. In this case the main advantage of the TBDMS group is that silicon always goes to an oxygen atom, so that the NH group of the tetrazole ring will remain unchanged. Subsequent deprotection of the primary alcohol can easily be achieved by treatment of the TBDMS derivative with a fluoride salt such as tetrabutylammonium fluoride. The entire reaction sequence is outlined for example in the attached presentation.

Good luck with your work and best wishes, Frank Edelmann

Dear Frank T. Edelmann

Thank you so much for your kind suggestion. I will try TBDMS protection.