Cyclopropenones. III. The Reaction of Diphenylcyclopropenone and Ammonia to Afford cis- and trans-3,4-Diphenylazetidinones

Abstract

Scheme 1

Reaction of diphenylcyclopropenone with 2-aminopyridines. Synthetic and mechanistic implications

“…It was possible to isolate 3 from chloroform solutions in better than 80% yield after recrystallization. These observations led to the formulation of the products as 3,4-dihydro-2fl-pyrido| l,2-a|pyrimidin-2-ones (4). A conformational representation of 4 shows that bonds a and b are capable of an antiperiplanar arrangement, thus facilitating a concerted olefin-forming elimination reaction.9 The cis nature of the bulky phenyl groups and the unfavorable H-6-phenyl interaction are other features which may contribute to R the instability of 4.…”

“…Received November 5,1974 Diphenylcyclopropenone (1) reacts with 2-aminopyridines (2) in ether to produce cis-2,3-diphenylacrylamides (3) and insoluble cis-3,4-dihydro-3,4-diphenyl-2fl-pyrido|l,2-a|pyrimidin-2-ones (4), which in chloroform solution readily rearrange to 3. In methanol, a slow reaction occurs, eventually forming 3 and 5, the stable trans isomers of 4.…”

“…The reaction of 1 with ammonia at -78°formed an unusual conjugate addition product (eq 3). 4 Recently, a carbonyl addition product (40% yield) was identified in the reaction of 1 with pyridine (eq 4)…”

On the Reactivity of α-(Triphenylphosphoranylidene)-benzylphenylketene with Nitrogen Compounds: Synthetic and Mechanistic Implications

“…A solution of 105.0 mg (0.5 mmol) of diphenylcyclopropenone (1) and 134.3 mg (0.5 mmol) of triphenylphosphine in 8.0 cm 3 of benzene in a two-necked roundbottom flask was left at room temperature with stirring for 2 h. To the orange solution was added 83.2 mg (0.5 mmol) of N-benzoylacetamidine (5). The solution turned yellow and was left stirring for 24 h. After this time the solvent was removed under reduced pressure and the residue was purified by column chromatography (Florisil  ) affording 15.7 mg (12%) of 14 (benzene/ethyl acetate 5%), 28.1 mg (13.5%) of 15 17 (benzene/ethyl acetate 5%) and 76.5 mg (67%) of α-phenylcinnamamide (13) 18 (benzene/ethyl acetate 10%). 14: IR (KBr): ν max /cm -1 3274, 1706, 1690, 1610.…”

Isothiourea-Catalyzed Asymmetric Synthesis of β-Lactams and β-Amino Esters from Arylacetic Acid Derivatives and N-Sulfonylaldimines

“…Applying these conditions to a small selection of arylacetic acids provided the corresponding 3,4-diaryl -lactams in moderate to good yield (42-77% yield), excellent diastereoselectivity (exclusively >95:5 dr) and in high levels of enantioselectivity (79-88% ee) ( Table 2). The relative configuration within -lactam 9 was assigned via a combination of nOe and coupling constant analysis (typically, J = 3.4 Hz), 29 with the absolute configuration assigned by analogy to - Although proceeding in excellent diastereo-and good enantioselectivity, this procedure suffers from typically moderate and often variable product yields that were not representative of reaction conversion. This was rationalized as being due to the instability of the -lactam products towards chromatographic purification and therefore a range of in situ derivatization methods was investigated.…”