PREPARATION OF MESO-3,6-BIS-(1-HYDROXY-1-PHENYLPROPYL)-1,2,4,5-TETRAZINES,( +/-)-3,6-BIS-(1-HYDROXY-1-PHENYLPROPYL)-1,2,4,5-TETRAZINES, MESO-3,6-BIS-(1-HYDROXY-1-PHENYLETHYL)-1,2,4,5-TETRAZINES, ( +/- )-3,6-BIS-(1-HYDROXY-1-PHENYLETHYL)-1,2,4,5-TETRAZINES, AND OPTICALLY ACTIVE FORMS OF 3,6-BIS-(1-HYDROXY-1-PHENYLPROPYL)-1,2,4,5-TETRAZINES AND 3,6-BIS-(1-HYDROXY-1-PHENYLETHYL)-1,2,4,5-TETRAZINES VIA A NEW SYNTHESIS OF 1,2-DIHYDRO-1,2,4,5-TETRAZINES FROM AMIDINES