The oxidation of ethyla luminum dichloride

Three-Component Synthesis of Substituted Perhydropyrans from β-Styrylmalonates, Aldehydes, and Alkoxyaluminum Dichlorides

“…However, we then noted that if the reaction of styrylmalonate 1a with benzaldehyde was performed with an “oxidized” sample of EtAlCl 2 obtained by preliminary exposure of an EtAlCl 2 solution in hexane in the presence of air (2 days in a vessel with a crack-open cap), not only did the reaction of 1a with aldehyde 2a occur, but the ethylidene moiety of the organoaluminum substrate was also unexpectedly involved in this reaction. Subsequent studies showed that the “oxidized” substrate was EtOAlCl 2 that was readily formed upon slow oxidation of EtAlCl 2 with atmospheric oxygen and matched the sample obtained previously . The same compound (EtOAlCl 2 ) can be selectively formed during long-term storage of a commercial EtAlCl 2 solution sample (during 1-2 years), but this process is too long and poorly controlled.…”

“…Subsequent studies showed that the "oxidized" substrate was EtOAlCl 2 that was readily formed upon slow oxidation of EtAlCl 2 with atmospheric oxygen and matched the sample obtained previously. 5 The same compound (EtOAlCl 2 ) can be selectively formed during long-term storage of a commercial EtAlCl 2 solution sample (during 1-2 years), but this process is too long and poorly controlled. This threecomponent reaction resulted in the regioselective formation of substituted dihydro-2H-pyran-3,3(4H)-dicarboxylate 4a (Scheme 2).…”

“…As a result, tetrahydro-2Hpyran-3,3(4H)-dicarboxylate 5a-d 2 was obtained in 59% yield, which contained deuterium atoms exclusively in the C(2) and C(4) positions of the perhydropyran ring. Moreover, the D atom in the CHD unit is strictly cis to the aryl substituent at C (5). Thus, we are dealing with a new unusual variant of the reactivity of the alkoxy fragment in an aluminum−organic substrate and, as a result, it is a supplier of a diatomic synthon with the formation of new O−C and α-C−C bonds as part of a six-membered cycle.…”