Sarawak Medichem Pharmaceuticals, Inc.

Medichem Research, Inc.

Wei Chen

Michael T Flavin

Ze-Qi Xu

John D Rizzo

Albert Khilevich

Lin Lin

Vilayphone Vilaychack

William A Boulanger

Abram Kivovich Sheinkman

Alla Kucherenko

A method of preparing (.+-.)-calanolide A, 1, a potent HIV reverse transcriptase inhibitor, from chromene 4 is provided. Useful intermediates for preparing (.+-.)-calanolide A and its derivatives are also provided. According to the disclosed method, chromene 4 intermediate was reacted with acetaldehyde diethyl acetal or paraldehyde in the presence of an acid catalyst with heating, or a two-step reaction including an aldol reaction with acetaldehyde and cyclization either under acidic conditions or neutral Mitsunobu conditions, to produce chromanone 7. Reduction of chromanone 7 with sodium borohydride, in the presence of cerium trichloride, produced (.+-.)-calanolide A. A method for resolving (.+-.)-calanolide A into its optically active forms by a chiral HPLC system or by enzymatic acylation and hydrolysis is also disclosed. Finally, a method for treating or preventing a viral infections using (.+-.)-calanolide or (-)-calanolide is provided.

Method for the preparation of (.+-.)-calanolide A and intermediates

Unprotected adenine, 6-chloropurine, 2,6-diaminopurine, and 2-amino-6-chloropurine have been directly coupled with 2-(diethoxyphosphonomethoxy)ethanol under a disclosed method to provide acyclic phosphonate nucleotide analogues which are intermediates for antiviral agents such as 9-�2-(phosphonomethoxy)ethyl!adenine (PMEA) and its analogues having a structure of formula I: ##STR1## wherein Z represents N or CH; R.sub.1 represents hydrogen, alkyl, aryl, or arylalkyl; R.sub.2 and R.sub.3 are independently selected from H, OH, halo, NH.sub.2, C.sub.6 H.sub.5 CH.sub.2 O, or R.sub.4 R.sub.5 N wherein R.sub.4 and R.sub.5 are independently selected from alkyl, aryl, or arylalkyl.

Method for the preparing �9-12-(Diethoxyphosphonomethoxy)ethyl!adenine

A method of preparing (.+-.)-calanolide A, 1, a potent HIV reverse transcriptase inhibitor, from chromene 4 is provided. Useful intermediates for preparing (.+-.)-calanolide A and its derivatives are also provided. According to the disclosed method, chromene 4 intermediate was reacted with acetaldehyde diethyl acetal or paraldehyde in the presence of an acid catalyst with heating, or a two-step reaction including an aldol reaction with acetaldehyde and cyclization either under acidic conditions or neutral Mitsunobu conditions, to produce chromanone 7. Reduction of chromanone 7 with sodium borohydride, in the presence of cerium trichloride, produced (.+-.)-calanolide A. A method for resolving (.+-.)-calanolide A into its optically active forms by a chiral HPLC system or by enzymatic acylation and hydrolysis is also disclosed. Finally, a method for treating or preventing viral infections using (.+-.)-calanolide A or (-)-calanolide A is provided.

Growing community of inventors

Naperville, IL, United States of America

Wei Chen