The amine-tetraalkyldiboroxanes I (R1-R4 = Et; R1 = R2 = R4 = Et, R3 = Ph; R1 = R2 = R3 = Et, R4 = Ph; R1 = R3 = R4 = Et, R2 = Ph) react on heating by EtBO elimination and allylborane rearrangement to yield the allylaminoboranes Me2NB(Et)CH2C(R2):C(R3R4): on heating above 60 Deg, the diastereomeric syn/anti-I (R1R3 = C8H14, R2 = R4 = Et; R1R4 = C8H14, R2 = R3 = Et) give the unsatd. rac-aminotrialkyldiboroxane II (x-ray structure anal.) by intramol. 1,2-deaminoboration. II is characterized by reaction with (Et2BH)2 and (Et2BD)2 with formation of the 1,2,6-oxadiborinane III by evolution of H2 or HD resp. The intramol. CH-borylation of II is compared with those of the thujopsen hydrocarbons.