164650-44-6

In October 2013, efinaconazole (also known as KP-103) was approved in Canada as a 10% topical solution for the treatment of onychomycosis. Like other azole antifungal agents, efinaconazole acts by disrupting fungal cell membranes through inhibition of sterol 14α-demethylase, an enzyme involved in the biosynthesis of ergosterol, which is a key component of the fungal cell membrane. Efinaconazole has potent antifungal activity against clinical isolates of dermatophytes, including Trichophyton mentagrophyes (MIC₈₀ =0.125 μg/mL) and Trichophyton rubrum (MIC₈₀ =0.25 μg/mL), as well as against Candida and Malassezia species. Unlike other antifungal agents, efinaconazole retains activity in the presence of keratin, indicating that more unbound drug is available at the site of action. Efinaconazole is efficacious in guinea-pig models of fungal infection. Efinaconazole is prepared by reaction of an epoxide intermediate with 4-methylenepiperidine.

Kaken Pharmaceuticals (Japan)

ChEBI: A member of the class of triazoles that is butan-2-ol which is substituted at positions 1, 2, and 3 by 1,2,4-triazol-1-yl, 2,4-difluorophenyl, and 4-methylenepiperidin-1-yl groups, respectively (the 2R,3R stereoisomer). It is an antifungal drug used for the topical treatment of onychomycosis (a nail infection caused mainly by dermatophytes).

Jublia

Efinaconazole is a triazole antifungal drug approved clinically for the treatment of nail fungus (Onychomycosis). It inhibits sterol biosynthesis by inhibition of cytochrome P450 14α-demethylase, an enzyme in the sterol biosynthesis pathway that leads from lanosterol to ergosterol. Efinaconazole has better nail penetration, so is more effective than other topical agents and as effective as oral medication for nail fungus.

Commercially available (R)-methyl lactate (55) was first converted to THP protected alcohol 57 in 4 steps and 78% yield via morpholino amide 56. Grignard displacement of the morpholine afforded ketone 58 in 81% yield. Next, ketone 58 was epoxidized by means of the Corey ylide followed by ring-opening of the epoxide by triazole which had been activated by exposure to sodium tbutoxide. Finally, subjection to methanesulfonic acid furnished diol 59 in 51% yield as the corresponding mesylate salt. Diol 59 was then converted to epoxide 60 through the use of mesyl chloride and triethylamine in 78% yield and >99% ee. Finally, treatment of epoxide 60 with 4-methylene piperidine¨CHBr in the presence of lithium hydroxide afforded efinaconazole (VIII) in 87% yield.

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[1] WILLIAM J JO SIU. Comparison of in vitro antifungal activities of efinaconazole and currently available antifungal agents against a variety of pathogenic fungi associated with onychomycosis.[J]. Antimicrobial Agents and Chemotherapy, 2013, 57 4: 1610-1616. DOI: 10.1128/aac.02056-12
[2] YOSHIYUKI TATSUMI. Mechanism of action of efinaconazole, a novel triazole antifungal agent.[J]. Antimicrobial Agents and Chemotherapy, 2013, 57 5: 2405-2409. DOI: 10.1128/aac.02063-12