Synthesis of Stereoisomeric 3‐Substituted Cyclobutanecarboxylic Acid DerivativesThe preparation of 3‐substituted cyclobutanecarboxylic acids by ring forming malonic ester cycloalkylation/saponification/decarboxylation leads to 50:50cis/transmixtures. Only some polar ester derivatives2can be separated by chromatographic methods. Catalytic hydrogenation of 3‐substituted cyclobutenecarboxylic acids3, however, gives thecisacids4with 90–95% selectivity. Reduction of the same acids3by Zn in aqueous HCl/THF leads to thetransacids6with 90–93% se