Tetralin → 1,2,3,4-Tetrahydroisoquinoline

HRID 1657412Notes

Reaction equation

HRID 1657412 reaction equation
[CH:1]1[C:10]2[C:5](=[CH:6][CH:7]=[CH:8][CH:9]=2)[CH2:4][CH2:3][N:2]=1.O=P12OP3(OP(OP(O3)(O1)=O)(=O)O2)=O.P(Cl)(Cl)(Cl)=O.P(Cl)(Cl)(Cl)(Cl)Cl.C1C2C(=CC=CC=2)CCC1.[BH4-].[Na+].[H][H]>[Pd].[Pt].Cl.[Cl-].[Zn+2].[Cl-].C1(C)C(C)=CC=CC=1.C1(C)C=CC=CC=1>[CH2:1]1[C:10]2[C:5](=[CH:6][CH:7]=[CH:8][CH:9]=2)[CH2:4][CH2:3][NH:2]1

Participants

14

Reactant 7

HCID 8404TetralinHCID 14812Phosphorus oxide (P4O10)HCID 24813Phosphorus oxychlorideHCID 24819Phosphorus pentachlorideHCID 767053,4-DihydroisoquinolineHCID 4311764Sodium borohydrideHCID 178418361HCID 178418361, compound3×

Product 1

HCID 70461,2,3,4-Tetrahydroisoquinoline

Reagents, catalysts & solvents 6

HCID 23938PalladiumCatalyst2×HCID 23939PlatinumCatalystHCID 3007855ZincchlorideCatalystHCID 313Hydrochloric AcidSolventHCID 1140TolueneSolventHCID 7237O-XyleneSolvent

Procedure

may be prepared by the cyclodehydration of the appropriately substituted β-phenethylamide to the corresponding 3,4-dihydroisoquinoline by heating the aforesaid amide in the presence of such dehydrating agents as phosphorus pentoxide, anhydrous zinc chloride, phosphorus oxychloride or phosphorus pentachloride, usually in an inert organic solvent like toluene, xylene or tetralin, followed by reduction in the usual manner, e.g., with sodium borohydride or with hydrogen and palladium-on-charcoal catalyst (the Bischler-Napieralski route); by condensation between the appropriately substituted benzaldehyde and 2-amino-acetaldehyde dialkyl acetal, followed by reduction of the Schiff base product, e.g., with hydrogen and platinum catalyst, and then hydrolysis/ring closure of the resulting N-benzylamino acetaldehyde dialkyl acetal in 6N hydrochloric acid solution, followed by selective reduction of the ring, e.g., with hydrogen and palladium-on-charcoal catalyst, to give the appropriate 1,2,3,4-tetrahydro-isoquinoline [Bobbitt et al., Journal of Organic Chemistry, Vol. 30, p. 2247 (1965), and Bobbitt and Sih, ibid., Vol. 33, p. 856 (1968)].

Sources & evidence

ORD record
ord-fb57b846d1a047109923bf3c03a74d0c
Source dataset
uspto-grants-1976_06
Patent number
US03960861

Reaction notes

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