This is from the book "The Life and Times of Jesus the messiah" by Alfred Edersheim
The Sadducees originally represented a reaction from the Pharisees-the moderate men, who sympathised with the later tendencies of the Maccabees. Josephus places the origin of these two schools in the time of Jonathan, the successor toJudas Maccabee(160-143BC).
He also says the Tsadoq(Zadok) comes from a 7th century Jewish legend, and has no support from Josephus or early Jewish writings. Concerning Tsadoq coming from the High Priest in Solomons time he says this:"But the objections to this are insuperable. Not to speak of the linguistic difficulty of deriving Tsadduqum (Zaddukim, Sadducees) from Tsadoq(Zadok), niether Josephus nor the Rabbis know anything of such a connection Tsadoq and the Sadducees ,of which, indeed,the rationale would be dificult to percieve".
He went on to say," the Sadducees must have given the name to their party, since it cannot be imagined that the Pharasees would have connected their opponents with the honoured name of the High Priest of Tsadoq."
Finally he says this: "while the pharisees would arrogate to themselves the Scriptual name of Chasidim, or 'the pious', their opponents would retort that they were satisfied to be Tsaddiqim,'or righteous'. Thus the name of Tsaddiqim would become that of the party opposing the Pharisees, that is, the Sadducees..............whether or not this suggestion approve itself to critics, the derivation of Sadducees fromTsaddiqim is certainly that which offers most probability".