Reaction of FeCl3 with 7-chloro-1-silyloxybicyclo[4-1-0]heptanes : A way to 2-(1-chloroalkylidene)cyclohexanones

Chemistry of Acyl Radicals

“…230 It is also readily seen from Figure 4 that the unambiguous generation of any fused cyclopropyloxyl radical akin to 46 will result in preferential cleavage of the endocyclic bond for kinetic, as well as thermodynamic, reasons. Indeed, this is known to be the case in practice, [231][232][233][234][235][236][237] unless cleavage of the exocyclic bond is favored by radical stabilizing sub-stituents. 237 Finally, it is again evident from this study that any mechanism for rearrangement of the kinetic closed product to the thermodynamic one involving cleavage to an acyl radical may be discounted.…”

“…Indeed, this is known to be the case in practice, [231][232][233][234][235][236][237] unless cleavage of the exocyclic bond is favored by radical stabilizing sub-stituents. 237 Finally, it is again evident from this study that any mechanism for rearrangement of the kinetic closed product to the thermodynamic one involving cleavage to an acyl radical may be discounted.…”

Iron Trichloride-Promoted Cyclization of o-Alkynylaryl Isocyanates: Synthesis of 3-(Chloromethylene)oxindoles

“…The formation of oxindoles 18 − 20 was explained by a stereoselective cationic cyclization, with attack of the imidoyl cation by the alkyne and addition of chloride ion in an anti fashion, producing the corresponding 3-(chloroalkylidene)oxindole iron alkoxide J . Homolytic scission of the O−Fe bond would generate an oxy radical K able to promote a remarkably efficient 1,5-hydrogen abstraction leading to the allylic radical L . Chlorine atom transfer from FeCl 3 would then produce the corresponding oxindoles 18 − 20 and FeCl 2 (Scheme )…”

Neighboring Group Participation in a Regio- and Stereoselective Chlorination of a Bicyclo[2.2.2]octanone

“…Other methods such as the sodium acetate-induced elimination of HCl from R-(1,1-dichloroethyl)cyclohexanone gave a 77/ 23 mixture of the (E)-and (Z)-products. 19 Still, the (E)isomer dominated. On the other hand, treatment of R-acetylcyclohexanone with oxalyl chloride was reported to give the (Z)-isomer as the major product, together with the isomer having the chlorine atom at the ring position.…”

“…β-Chloro-α,β-unsaturated ketones synthesized from α-allenones and SnCl 4 were reported to have the ( E )-configuration, in agreement with our results. Other methods such as the sodium acetate-induced elimination of HCl from α-(1,1-dichloroethyl)cyclohexanone gave a 77/23 mixture of the ( E )- and ( Z )-products . Still, the ( E )-isomer dominated.…”