The unusual stereochemical behaviour of ferrocenecarboxaldehyde in reaction with chiral alkylammonium hypophosphite

The reaction of aldehydes with chiral α-methylbenzylammonium hypophosphite, which, in majority of cases led exclusively to one diastereoisomer, turned out to be much less stereoselective in case of ferrocenecarboxaldehyde. Attempts have been undertaken to explain it.