2.4- Diphenyl-2-pyrroline

The submitters state that distillation yields pure 2,4-diphenyl-2-pyrroline, b.p. 170-172°/3 mm., 203-205°/8 mm., which solidifies on cooling (yield 80-90%). 

The product is sufficiently pure for most purposes. Recrystallization from toluene gives a 90-93% recovery of a very light green product, m.p. 179-180° (cor.). The submitters state that the product obtained in the first crystallization has this melting point if the 2,4-diphenyl-2-pyrroline is purified by distillation before dehydrogenation. 

Diphenylpyrrole has been prepared only by dehydrogenation of 2,4-diphenyl-2-pyrroline with selenium, Raney nickel, and nickel supported on pumice.6... 

Diphenyl-2-pyrroline, 27, 33 Diphenyl selenide, 24, 91 Diphenylthiocarb azide, 25, 38 Diphenylthiocarbazone, 25, 38 Dl- -PROPYI.AMINOETIIYI.AMINE, 23, 24 y-Di-n-propylaminopropylamine, 24, 46 Disproportionation, of diphenylthio-... 

Independent work by Schmid93 and by Padwa94 on the photochemistry of 2H-azirines has shown that irradiation of such systems leads in the first instance to the formation of nitrile ylids (nitrilium betaines). Subsequent 1,3-addition to a variety of dipolarophiles affords five-membered heterocycles. These additions take place in a stereospecific and regioselective manner thus, irradiation of the diphenyl-2f/-azirine 117 in the presence of dimethyl maleate leads to the formation of the two isomeric 1-pyrrolines... 

Arylidene alkylamines and diphenyl cyclopropenone gave rise to products 397-399, whose formation can be interpreted by means of oxidative secondary reactions of the 5 H-A2-pyrrolin-4-one 396 (R2 = H) initially generated252. ... 

High degrees of enantioselectivity have been observed when alkylzinc reagents react with aldehydes in the presence of chiral ligands.120 Among several compounds that have been used as ligands are exo - (dime th y I a m i no )no rb o rn c o I (A)121 122 123 124 and diphenyl(l-methyl-pyrrolin-2-yl)methanol (B) as well as ephedrine derivatives C and D. 

Racemic methadone (MET) is administered to heroin addicts as a substitution therapy. However, methadone enantiomers possess different pharmacological effects, and the drug has been demonstrated to be enantioselectively metabolized to its two major metabolites, 2-ethylidene-l,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) and 2-ethyl-5-methyl-3,3-diphenyl-l-pyrroline (EMDP). Stereoselective separation of MET, EDDP, and EMDP using an alpha-glycoprotein stationary phase and MS-MS detection was proposed by Kelly et al. [34]. Optimal separation conditions were 20 mM acetic acid isopropanol (93 7, pH 7.4), with a flow rate of 0.9mL/min. 

A recent adaptation of this type of approach involves the spontaneous intramolecular cyclization of imino ketones, formed by the reduction of nitro ketones through the action of tributylphosphine/diphenyl sulfide (Scheme 6.14). When the corresponding esters (R = OR) are used, pyrrolin-2-ones are formed (Scheme 6.15). 

Reaction of the 2-acetoxy-3(2//)-furanones (526) with monosubstituted hydrazines gives good yields of the pyridazinium-5-olates (527) together with varying amounts of isomeric products. Alkyl derivatives (527 R = alkyl) have also been prepared by base-catalyzed alkylation (Mel, Me2SO4, PhCH2Cl) of 3-methyl-6-phenyl-5-ethoxycarbonyl-4( 1 //)-pyridazinone. Reduction of the diphenyl compound 527 (R = Ar = Ph) by zinc and hydrochloric acid gives 3-ethoxycarbonyl-5-hydroxy-5-methyl-l,2-diphenyl-2-pyrrolin-4-one (528 R = Ar = Ph) (Scheme 21... 

Benzyl cyanide under similar conditions reacts with 2-phenyl-1-azirine to give 3,4-diphenyl-2-oxo-5-iminopyrroline (153). The imino-pyrroline (152) is probably produced initially and is air-oxidized to the final product. 

Kitamura et al. also concluded that the ease of vinyl cation formation based on the leaving group was Cl > Br > I which corroborates the evidence found on irradiation of the l,l-diphenyl-2-haloethenes [62], but contrasts with the work of Kropp et al. [57-59,61]. Further evidence for a vinyl cation was uncovered in the photolysis of the a-phenyl-/ ,/ -anisyl vinyl bromide which is illustrated in Scheme 23. A pyrroline product via intermediate E was formed in high yield, which reveals a 1,2-cationic anisyl shift [66],... 

Gas Chromatography. System GA—methadone RI 2148, 2-ethylidene-l,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) RI 2030, 2-ethyl-5-methyl-3,3-diphenyl-l-pyrroline (EMDP) RI 1950 system GB—RI 2124 system GC—RI 2470 system GF— methadone RI 2370, EDDP RI 2280, EMDP RI 2190. 

Similar ring contractions in which the nitrogen-nitrogen bond is cleaved are found in the reductive ring contractions of pyridazines to pyrroles [148, 149], phthalazines to isoindoles [150], 5,6-diphenyl-1,2,4-triazinones to imidazolones [151], benzo-l,2,4-triazines to benzimidazoles [71], benzo-l,2,3-triazinone to indazolone [la, 152], benzo-l,2,3-triazin-3-oxide to indazole [la], benzo-2,3-diazepines to isoquinolines [153], benzo-l-pyrano-[4,3-e ]-as-triazin-3-one to benzopyranoimidazolone [154], and 2-methyl-4,5-dihydropyridazin-3-ones to pyrrolin-2-ones [155]. 

An interesting cyclization reaction occurs with methadone on N-dcmcthylation. The demethylated metabolite normeth-adonc undergoes spontaneous cyclization to form the en-amine metabolite 2-ethylidenc-I.S-dimethyl-3.3-diphenyl-pyrrolidine (EDDP)."" Subsequent N-demethylation of EDDP and isomerization of the double bond leads to 2-ethyl-5-methyl-3.3-diphenyl-l-pyrroline (EMDP). 

Irradiation of the 1,2-oxazines (208) affords a variety of products, depending on the groups at position 6. The 6-unsubstituted material (208 R = H) gives the hydroxy-pyrroline (209) (100%) whereas the diphenyl analogue (208 R = Ph) gives the oxime (210) (80%) the different products that are... 

Reaction with phosphorus compounds. Hydrozirconation of vinyl(diphenyl)-phosphine at C-l is feasible, while ring cleavage of l-phenylphospha-3-cyclopentene to give homoallylic phosphines is observed. (l-Benzyl-3-pyrroline and dihydro-furan also undergo similar cleavage.)... 

The addition of phosphorous acid to 3,4-dihydroisoquinoline gives 1,2,3,4-tetra-hydroisoquinoline-1-phosphonic acid (192), and that of diphenyl hydrogenphosphonate to 2/f-pyrroline yields the diphenyl ester of Pro (193). ... 

Diphenyl-Ai-p-tolylketenimine reacts with 2-dimethylamino-3-(methyl)phenylazirine 81 to give 2-dimethylamino-3-methyl-3,4,4-triphenyl-5-p-tolylimino-l-pyrroline 82 in 57 % yield... 

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