1. Field of the Invention
The present invention relates to processes and intermediates for preparing 4-amino-5-biphenyl-4-yl-2-hydroxymethyl-2-methyl-pentanoic acid compounds that are useful in preparing compounds having neprilysin-inhibition activity.
2. State of the Art
Commonly-assigned U.S. Patent Application Publication 2012/0213806 to Fleury et al., discloses compounds that have activity as neprilysin inhibitors, the disclosure of which is incorporated herein by reference. In one embodiment, this application discloses compounds such as (2S,4R)-5-biphenyl-4-yl-2-hydroxymethyl-2-methyl-4-[(3H-[1,2,3]triazole-4-carbonyl)-amino]-pentanoic acid 5-methyl-2-oxo-[1,3]dioxol-4-ylmethyl ester and its tautomer (2S,4R)-5-biphenyl-4-yl-2-hydroxymethyl-2-methyl-4-[(1H-[1,2,3]triazole-4-carbonyl)-amino]-pentanoic acid 5-methyl-2-oxo-[1,3]dioxol-4-ylmethyl ester.
When preparing compounds for long term storage and when preparing pharmaceutical compositions and formulations, it is often desirable to have a crystalline form of the therapeutic agent that is neither hygroscopic nor deliquescent. It is also advantageous to have a crystalline form that has a relatively high melting point, which allows the material to be processed without significant decomposition. A crystalline form of (2S,4R)-5-biphenyl-4-yl-2-hydroxymethyl-2-methyl-4-[(1H-[1,2,3]triazole-4-carbonyl)-amino]pentanoic acid 5-methyl-2-oxo-[1,3]dioxol-4-ylmethyl ester is disclosed in commonly-assigned U.S. Provisional Application No. 61/599,023, filed on Feb. 15, 2012, and entitled “Crystalline Form of (2S,4R)-5-Biphenyl-4-yl-2-hydroxymethyl-2-methyl-4-[(1H-[1,2,3]triazole-4-carbonyl)amino]pentanoic Acid 5-Methyl-2-oxo-[1,3]dioxol-4-ylmethyl Ester”, the disclosure of which is incorporated herein by reference.
The compounds disclosed in these publications and applications are prepared by techniques that typically require a diastereomically pure starting material and where one or more intermediates are purified by chromatography. There are several advantages to developing processes where such purification steps are not necessary. This invention addresses that need.