Diphenyl-propenone

Cathodic reduction of 1,3-diphenyl-propenone leads to l-hydroxy-2-benzoyl-3,4-diphenyl cyclopentanes with exclusive cis configuration of the two phenyl groups. With l-phenyl-l-pentene-3-one the cyclodimer 2-methyl-3,5-diphenyl-4-(l-propionyl)-cyclohexanone is formed with a 100% yield in an intramolecular Michael addition via an electrogenerated base. The substituents are all in the most stable equatorial position [277]. 

The Soos group, in 2005, prepared the first thiourea derivatives from the cinchona alkaloids quinine QN (8S, 9R-121), dihydroquinidine DHQD (8S, 9S-122), C9-epi-QN (8S, 9P-123), and quinidine QD (SR, 9R-124) via an experimentally simple one-step protocol with epimerization at the C9-position of the alkaloid starting material (Figure 6.39) [278]. The catalytic efficiency of these new thiourea derivatives and also of unmodified QN and C9-epi-QN was evaluated in the enan-tioselective Michael addition [149-152] of nitromethane to the simple model chal-cone 1,3-diphenyl-propenone resulting in adduct 1 in Scheme 6.119. After 99h reaction time at 25 °C in toluene and at 10 mol% catalyst loading QN turned out to be a poor catalyst (4% yield/42% ee (S)-adduct) and C9-epi-QN even failed to accelerate the screening reaction. In contrast, the C9-modified cinchona alkaloid... 

Figure 6.39 Cinchona alkaloid-thioureas prepared from quinine (121), dihydroquinine (122), C9-epi-quinine (123), and quinidine (124) catalytic efficiency evaluated in the Michael addition of nitromethane to tram-chalcone 1,3-diphenyl-propenone at 10mol% loading and rt.

The presented protocol tolerated a spectrum of enolizable species including dialkyl malonates, 1,3-diketone, ketoester, 1,3-dinitriles, and nitroesters to be added to the model trons-chalcone 1,3-diphenyl-propenone producing the desired Michael adducts in good to excellent yields (67-99%) and with attractive ee values (88-93%). Figure 6.41 shows some selected results of the nucleophile evaluation. 

Scheme 6.140 Proposal for the role of catalyst 121 in the Michael reaction between O-benzylhydroxylamine and 1,3-diphenyl-propenone.

A limitation of this method becomes obvious in the reaction of 2 with ( )-l,3-diphenyl-propenone (chalcone). Here, the addition of the ylide takes place at the carbonyl group, and l-methylsulfanyl-2,4-diphenylbutadiene is formed. 

Attempts were reported119,129 to synthesize the ortho-linked diphenyl cyclo-propenone phenanthreno cyclopropenone 173 by dehydrohalogenation of the dibromo derivative 174 of dibenzo cyclohepta-l,3-diene-6-one. The only product isolated was the anhydride 175 of phenanthrene-9-carboxilic acid, which was shown not to arise from 173l29 ... 

BINOL (57 mg, 0.2 mmol) was placed in a 50-ml Schlenk flask equipped with a magnetic stirring bar under an inert atmosphere and dissolved in dry diethyl ether (4 ml). After cooling the solution to 0°C with an ice-bath, diethylzinc (0.18 ml, 0.2 mmol, 1.1 M solution in toluene) was added whilst stirring. After three hours the complete precipitation of an amorphous white solid was observed and ( )-l,3-diphenyl-2-propenone (0.21 g, 1 mmol) and cumene hydroperoxide (0.22 ml, 1.2 mmol, 80% solution in cumene) were added stirring of the reaction mixture at room temperature was maintained for one hour. 

The reaction of diphenylsulfonium 2-propcnylide with ( )-l,3-diphenyl-2-propenone provides the ethenvl-substituted cyclopropylketone 18 with moderate simple diastereoselectivity13. The S-ylide intermediate 17 is generated by deprotonation of the corresponding sulfonium salt. 

The first derivative to be isolated, in 1959, was diphenylcyclo-propenone [8, 9], which was a stable compound. Again in the case of cyclopropenones, alkyl derivatives were then prepared to check that the stability was not due largely to the substituent phenyl groups [10]. The alkylcyclopropenones are moderately sensitive to oxygen but in other respects are remarkably stable. Thus dipropylcyclopropenone is more stable to both heat and alkali than is diphenyl-cyclopropenone. 

The aldol reaction (aldol condensation) is one of the fundamental reactions of organic chemistry because it leads to the formation of a new carbon-carbon bond (see Experiment [20] for a very similar example of the Qaisen-Schmidt type of aldol reaction). In this version, the condensation of 4-nitrobenzaldehyde (an aldehyde without an a-hydrogen atom) with acetophenone (a ketone) gives frans-4-nitrochalcone.The aldol condensation of the unsubstituted aromatic aldehyde, benzaldehyde with acetophenone, yields frans-l,3-diphenyl-2-propenone (PhCH CHCOPh), which has the common name, chalcone.Thus, the substituted derivatives of this system are known collectively as chalcones. 

Cyc/o propanone [189] absorbs at 1813 cm" and its 2 3-dichloro derivative [190] at 1822 cm" Much interest has been aroused by cyc/o propenone which has been studied by a number of workers. Two bands are shown by all derivatives. The 2 3-dichloro derivative [191] absorbs at 1886 and 1615 cm", and the diphenyl derivative [192, 193] at 1850 and 1640 cm" Both the C=C and the CO frequencies would be expected to be high in these compounds, so that they are difficult to identify in terms of individual group frequencies. Attempts have been made to do so using solvent shift techniques, and these suggest that the lower frequency band has more carbonyl character. 

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