1,3,4,6,7,8-Hexahydro-1-methyl-2H-pyrimidol[1,2-a]pyrimidine

Step 1: Synthesis of TBD from Guanidine Hydrochloride:

Add guanidine hydrochloride (95g, 1mol, 1eq) and 3,3-diaminodipropylamine (131g, 1mol, 1eq) to a flask. Heat to 120℃ to initiate the reaction, and then continue heating to 150℃ for 8 hours. Cool to 70℃, add 300ml of methanol, and stir to dissolve.

Step 1: Synthesis of TBD from Guanidine Hydrochloride:

In a flask, add guanidine hydrochloride (95g, 1mol, 1eq) and 3,3-diaminodipropylamine (131g, 1mol, 1eq). Heat to 120℃ to initiate the reaction, and then continue heating to 150℃ to react for 8 hours.

Add 200 ml of methanol solution containing 1 mol sodium methoxide, concentrate to remove most of the methanol, add 300 ml of dichloromethane, filter, recrystallize the filter cake in 300 ml of tetrahydrofuran, filter, wash the residue with 100 ml of THF, and dry to obtain approximately 120 g of TBD, yield 86%. Step 2: Synthesis of MTBD from TBD: Add TBD (50 g, 1 eq), potassium hydroxide (24 g, 1.2 eq), and 250 ml of tetrahydrofuran sequentially to a flask. Add dimethyl sulfate (45.26 g, 1 eq) dropwise at room temperature. Let the reaction proceed overnight at room temperature. The next day, filter, concentrate the filtrate, and distill the residue to obtain MTBD (46.8 g, yield 85%).

Colorless liquid

7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene may be used in microwave-promoted, palladium-catalyzed C-N bond-forming reactions with aryl/heteroaryl nonaflates and amines. It may be used as strong base to investigate the podand solvents, tris(oxaalkyl)phenylsilanes and tris(oxaalkyl)phosphates.

7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene is a soluble amine base. It forms 1:1 complexes with 4-nitrophenyl[bis(diethylsulfonyl)]methane and phenyl[bis(diethylsulfonyl)]methane and their structures have been studied by FT-IR, ¹H NMR and PM5 semiempirical methods. Catalytic performance of 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene for the transesterification of rapseed oil with methanol has been investigated.