Cyclopropane carbonitrile

NHase from Rhodococcus. sp. AJ270 was isolated, purified, and applied to the enantiose-lective transformation of a series of cyclopropane carbonitriles. Amides with moderate ee were isolated from conversion of many of the cyclopropane substrates, to yield the amides trans-( IR, 2/ )-3-phenylcyclopropane carbonitrile (49% conv. 22.7% ee), trans-( IS, 35)-2,2-dimethyl-3-phenylcyclopropanecarbonitrile (40% conv. 84.7% ee), trans-( IR, 3/f)-2,2-dibromo-3-phenylcy-clopropanecarbonitrile (11.6% conv. 83.8% ee), cis-( IR, 25)-3-phenylcyclopropanecarbonitrile (25.8% conv. 95.4% ee), and cis-(lR, 2S )-2,2-dimethyl-3-phenylcyclopropanecarbonitrile (7.9% conv. 3.2% ee) [43],... 

The thermolysis (- 10 to -t- 25°C) or photolysis (2 > 300 nm, - 10°C) of 3//-diazirine-3-car-bonitriles generates cyanocarbenes under very mild reaction conditions (see Houben-Weyl, Vol. E19b, pl206). Their addition to electron-rich alkenes yielded cyclopropane carbonitriles in moderate yields (Table 3). The 3//-diazirines-3-carbonitriles were prepared from 3-halodiazirines, mostly in situ, by an exchange reaction with tetrabutylammonium cyanide. The cyclopropanation of (Z)- or ( )-but-2-ene proceeded nonstereospecifically, which is explained by the participation of a triplet carbene. 

When one hydrogen atom is replaced by a functional group, four isomers are formed in the process of the structural isomerization. Calculations [47] and experimental study [48,49] were performed on cyclopropane carbonitrile (C3H5CN), where the functional group is a -C = N group. 

The quantum chemical calculations show that the first three isomers are produced via two transition states and one intermediate each. Methacrylonitrile is obtained directiy from the cyclopropane carbonitrile via one transition state with no intermediates. 

FIGURE 6.2 Reaction schemes for cyclopropane carbonitrile isomerizations to cis-, trans-crotonitrile, and vinyl acetonitrile (channel 1). All the energy values are calculated relative to the reactant. 

FIGURE 6.3 Reaction schemes for cyclopropane carbonitrile isomerizations to methacry-lonitrile (channel 2). 

FIGURE 6.4 Comparison between the calculated [47] and experimental [48,49] rate constants of the cyclopropane carbonitrile isomerizations. 

The isomerization of cyclopropane carboxaldehyde to propenyl aldehyde involves an opening of the cyclopropane ring and H-atom shift to form a methyl group. The pathway for this process is very similar to the one that has been found for cyclopropane carbonitrile that has been described in Section 6.2.2. 

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