Synthesis of tetrahydro-GGPP. (a) SeO2, t-BuOOH, salicylic acid, DCM; ii. NaBH4, EtOH (27% - 2 steps); (b) DIEA, (EtO)2POCl, Et2O (76%); (c) Mg powder, Et2O; (d) 28, THF, 18 hr. (15%); (e) PPTS, EtOH, 70°C (70%); (f) NCS, DMS, DCM, 2.5 hr.; (g) (NBu4)3HP2O7, ACN, 3 hr (52% - 2 steps).