Synthesis, X-ray Structure and Photo Chemistry of 2-(Methyl(1-Phenylvinyl)Carbamoyl)Phenyl Acetate

Abstract

2-(Methyl(1-phenylvinyl)carbamoyl)phenyl acetate (SM), empirical formula C₁₈H₁₇NO₃, crystallizes in the triclinic space group, P−1, with unit cell parameters a = 9.10870(10) Å, b = 10.56940(10) Å, c = 16.1340(2) Å, α = 78.0590(10)°, β = 89.5080(10)°, γ = 86.6830(10)°, Z = 4. The 2-(methyl(1-phenylvinyl)carbamoyl)phenyl acetate (SM) molecule, upon irradiation of UV-light below 3,000 Å, releases acetate group to give six membered cyclic lactam 1 as the major product. The quantum yield for the lactam 1 was found to be 0.053. An alternate conrotatory 6-pi electron photochemically allowed electrocyclic ring closure reaction also occurs upon irradiation to give a six-membered cyclic zwitterionic intermediate which retains acetate as leaving group. A [1,5]-H shift would then give the isomerized product 2. The quantum yield for the lactam 2 was found to be 0.026. A minor oxidation product lactam 3 that retains the leaving group also formed, likely from loss of a proton and tautomerization of enol. The loss of one hydrogen molecule is the driving force for revival of aromaticity in the minor product 3. The quantum yield for the lactam 3 was found to be 0.012. The low value of total quantum yield (0.091) for photocyclization of SM can be explained as the photoproducts absorb light in competition with the photoreactant.

Graphical Abstract

In this study, Synthesis, X-ray structure and photochemistry of 2-(methyl(1-phenylvinyl)carbamoyl)phenyl acetate (SM) is reported

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