Artificial banana flavor was derived from natural banana flavor; bananas, both Gros Michel and Cavendish, as well as other varieties including "wild" bananas, contain isoamyl acetate, amyl acetate and related compounds which result in their smell and taste.

The synthesis of isoamyl acetate from other sources (namely the reaction of isopentanol aka amyl alcohol with acetic acid as found in vinegar; the acid deprotonates the alcohol to form an ester) allowed for the replication of banana flavoring; however, because it's only one such compound in the full palette of "banana oil", it produces a one-note flavor. That flavor is recognizable as banana, by taste and smell, but it was never meant to be an accurate reproduction of any one variety of banana; merely a cheap reproduction of the species in general.

Other similar synthetics that have come to dominate use of the natural flavoring include methyl salicylate (the key ingredient of oil of wintergreen, and so close that hardly anybody bothers with the natural stuff anymore), and hydroxymethoxybenzaldehyde aka vanillin, used in most brands of vanilla ice cream (and other flavors; it adds a creamier flavor to chocolate, for instance).

Source: Dr. Derek Lowe, synthetic organic chemist, and FDA documentation on artificial food flavorings.

Artificial banana flavor was derived from natural banana flavor; bananas, both Gros Michel and Cavendish, as well as other varieties including "wild" bananas, contain isoamyl acetate, amyl acetate and related compounds which result in their smell and taste.

The synthesis of isoamyl acetate from other sources (namely the reaction of isopentanol aka amyl alcohol with acetic acid as found in vinegar; the acid deprotonates the alcohol to form an ester) allowed for the replication of banana flavoring on a mass-producible scale without the need for natural banana extracts; however, because it's only one such compound in the full palette of "banana oil", it produces a one-note flavor. That flavor is recognizable as banana, by taste and smell, but it was never meant to be an accurate reproduction of any one variety of banana; merely a cheap reproduction of the species in general.

Other similar synthetics that have come to dominate use of the natural flavoring include methyl salicylate (the key ingredient of oil of wintergreen, and so close that hardly anybody bothers with the natural stuff anymore), and hydroxymethoxybenzaldehyde aka vanillin, used in place of natural vanilla extract in most brands of vanilla ice cream (and other flavors; it adds a creamier flavor to chocolate, for instance).

Source: Dr. Derek Lowe, synthetic organic chemist, and FDA documentation on artificial food flavorings.