Deep desulfurization of hydrocarbon feeds containing undesired organosulfur compounds to produce a hydrocarbon product having low levels of sulfur, i.e., 15 ppmw or less of sulfur, is achieved by first subjecting the entire feed to an extraction zone to separate an aromatic-rich fraction containing a substantial amount of the aromatic refractory and sterically hindered sulfur-containing compounds and an aromatic-lean fraction containing a substantial amount of the labile sulfur-containing compounds. The aromatic-rich fraction is contacted with isomerization catalyst, and the isomerized aromatic-rich fraction and the aromatic-lean fraction are combined and contacted with a hydrotreating catalyst in a hydrodesulfurization reaction zone operating under mild conditions to reduce the quantity of organosulfur compounds to an ultra-low level.