Tetrahydrofuran → Dicyclohexylcarbodiimide

HRID 264041Notes

Reaction equation

HRID 264041 reaction equation
[C:1]([N:8]1[CH:12]=[CH:11]N=C1)([N:3]1[CH:7]=[CH:6]N=C1)=O.O1[CH2:17][CH2:16][CH2:15][CH2:14]1>C(Cl)Cl>[CH:12]1([N:8]=[C:1]=[N:3][CH:7]2[CH2:6][CH2:17][CH2:16][CH2:15][CH2:14]2)[CH2:11][CH2:17][CH2:16][CH2:15][CH2:14]1

Participants

4

Reactant 2

HCID 8028TetrahydrofuranHCID 682631,1'-Carbonyldiimidazole

Product 1

HCID 10868Dicyclohexylcarbodiimide

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

Malonitrile is alkylated (or dialkylated) by treatment with NaH in an appropriate solvent such as dimethylformamide or tetrahydrofuran at 0° to 25° C. to give compounds (51). Treatment of the substituted nitrile with (n-Bu)3SnN3 in refluxing dioxane for 24 hours gives, after acidic hydrolysis, the tetrazole (52), which is then alkylated with an alkyl halide (R4Br) in CH3CN employing Et3N as base to give a mixture of regioisomers (53) and (54). The regioisomers are then separated by flash chromatography and each nitrile is then reduced to the corresponding aldehydes (55) and (56) by treatment with Raney nickel in formic acid at 60° C. The resulting aldehydes are then treated with a stabilized ylide such as ethyl(triphenylphosphoranylidene)acetate in CH2Cl2 at room temperature to give (57) and (58) which are reduced catalytically using hydrogen gas, Pd/C as catalyst in methanol or ethanol at room temperature to give esters (59) and (60). These are then hydrolyzed to the corresponding acids (61) and (62) by treatment with alcoholic (MeOH/EtOH) alkali metal hydroxide (NaOH or KOH) at reflux. The acids are then coupled with an appropriate amine employing carbonyldiimidazole in tetrahydrofuran at room temperature or dicyclohexylcarbodiimide in CH2Cl2 at 0° C. to give amides (63) and (64).

Workup

  1. customat room temperature

Sources & evidence

ORD record
ord-5999b7727a80434b8f197955b5a847fe
Source dataset
uspto-grants-1997_07
Patent number
US05646170

Reaction notes

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