{{#invoke:Infobox|infobox}} (4S)-beta-phellandrene synthase (geranyl-diphosphate-cyclizing) (EC 4.2.3.52, phellandrene synthase, (−)-beta-phellandrene synthase, (−)-(4S)-beta-phellandrene synthase) is an enzyme with system name geranyl-diphosphate diphosphate-lyase (cyclizing; (4S)-beta-phellandrene-forming).<ref>{{#invoke:Citation/CS1|citation |CitationClass=journal }}</ref><ref>{{#invoke:Citation/CS1|citation |CitationClass=journal }}</ref><ref>{{#invoke:Citation/CS1|citation |CitationClass=journal }}</ref><ref>{{#invoke:Citation/CS1|citation |CitationClass=journal }}</ref> This enzyme catalyses the following chemical reaction

geranyl diphosphate <math>\rightleftharpoons</math> (4S)-beta-phellandrene + diphosphate

This enzyme requires ion Mn²⁺.