:Diphenylcyclopropenone

Diphenylcyclopropenone triggers an immune response that is thought to oppose the action of the autoreactive cells that otherwise cause hair loss.[http://www.ema.europa.eu/docs/en_GB/document_library/Orphan_designation/2009/10/WC500006138.pdf Public summary of positive opinion for orphan designation of diphenylcyclopropenone for the treatment of alopecia totalis] {{Webarchive|url=https://web.archive.org/web/20171222052309/http://www.ema.europa.eu/docs/en_GB/document_library/Orphan_designation/2009/10/WC500006138.pdf |date=22 December 2017 }}, European Medicines Agency. Document Date: London, 23 April 2009. Doc.Ref.:EMEA/COMP/428277/2006 One hypothesis is that in response to DPCP treatment, the body will attempt to downregulate inflammation through a variety of pathways, resulting in a downregulation of the autoimmune response at the hair follicle. This autoinflammatory reaction would otherwise destroy body's hair follicles.

A study of 41 alopecia areata patients showed significant hair regrowth in 40% at 6 months, being sustained in two thirds of these after a 12-month-follow up-period.{{cite journal | vauthors = Sotiriadis D, Patsatsi A, Lazaridou E, Kastanis A, Vakirlis E, Chrysomallis F | title = Topical immunotherapy with diphenylcyclopropenone in the treatment of chronic extensive alopecia areata | journal = Clinical and Experimental Dermatology | volume = 32 | issue = 1 | pages = 48–51 | date = January 2007 | pmid = 17004987 | doi = 10.1111/j.1365-2230.2006.02256.x | s2cid = 43725892 }}

In a 2002 study for the treatment of warts, the responders consisted of 135 individuals (87.7%) that had complete clearance of warts. Reported adverse effects were local and included with pruritus (itching) (15.6%), with blistering (7.1%), and with eczematous reactions (eczema)(14.2%). The majority of the patients tolerated the treatment very well. One patient developed local impetigo (minor infection). Patients had an average of 5 treatments over a 6-month period.

The chemical properties of diphenylcyclopropenone are dominated by the strong polarization of the carbonyl group, which gives a partial positive charge with aromatic stabilization on the cyclopropene (cyclopropenium) ring and a partial negative charge on oxygen. The steric hindrance and partial charge on the cyclopropenium inhibit further electrophilic aromatic substitution there, but the phenyl rings are reactive. The cyclopropenium acts as a meta director.{{cite encyclopedia|doi=10.1002/047084289X.rn01532|title=Diphenylcyclopropenone|first1=Tristan H.|last1=Lambert|first2=Eric D.|last2=Nacsa|encyclopedia=Encyclopedia of Reagents for Organic Synthesis|publisher=John Wiley & Sons}}

Electrophilic Lewis acids stabilize the charge separation, forming diphenylcyclopropenium ether or ester salts. Such compounds are extremely reactive electrophiles.

Conversely, the oxygen is quite nucleophilic. Lux-Flood acids can abstract the oxygen: thus activated isocyanates effect imines; phosphorus sulfides or activated thioic acids effect the thione, and a wide variety of electrophilic chlorinators, including oxalyl chloride, thionyl chloride, and phosphorus pentachloride, effect 3,3{{nbh}}dichloro-1,2{{nbh}}diphenyl­cyclopropene. The latter sees primary application as an electrophilical chlorinator itself, and catalyzes the action of the aforementioned chlorinators. However, 3,3{{nbh}}dichloro-1,2{{nbh}}diphenyl­cyclopropene also ligates palladium for cross-coupling reactions,{{Cite book|last=Bennett|first=Clay S.|chapter=3,3-Dichloro-1,2-diphenylcyclopropene|date=2012|title=Encyclopedia of Reagents for Organic Synthesis|publisher=John Wiley & Sons|language=en|doi=10.1002/047084289x.rn01514|isbn=978-0471936237 }} and reacts with trichloroacetate to give diphenylcyclobutenedione upon aqueous workup.

In other respects, the carbonyl is a typical electrophile, adding Grignard reagents, Knoevenagel enols, and enamines. The central ring is highly strained, and the presence of most transition metals or heating to 160 °C induces decarbonylation, although heating just below the decarbonylation temperature (150 °C) irreversibly forms a [3+2] dimer instead. Soft nucleophiles that typically add in conjugate typically open the ring instead, as do naïve attempts at reduction. However, careful hydroboration can reduce away the carbonyl.

• Benzophenone
• Cyclopropenone

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Category:Dermatologic drugs

Category:Ketones

Category:Cyclopropenes

Category:Phenyl compounds