Soai himself had written a 1992 Chemical Review on the enantioselective addition of organozinc reagents to aldehydes, which included a section entitled "Asymmetric Self-Catalytic Reaction" in which he noted that if "the structures of the product and the chiral catalyst are the same (chiral self-recatalyst), the reaction system becomes a real self-reproduction system for chiral molecules." Soai had recently introduced the dialkylzinc alkylation of pyridine carbaldehydes (Scheme 6a), which fits criterion 1 of the Frank model, authentic autocatalysis. However, amplification of enantiomeric excess up to or beyond that of the catalyst/product employed had not yet been achieved. Several other substrate classes were also shown to afford autocatalytic reactions (Scheme 6b and 6c ), again, however, achieving lower ee in the newly formed product than that of the catalyst. Scheme 6. Asymmetric autocatalytic dialkylzinc alkylation reactions reported by Soai. a) pyridine carbaldehydes; 18 b) ferrocenyl aldehydes; c) dialdehydes; d) pyrimidyl aldehydes. The reaction highlighted in part d) is the first example of amplification of product ee as well autocatalysis.