Crystal structure of 3-(benzhydrylcarbamoyl)-2-benzyl-6,7-dimethoxy-1- phenyl-1,2,3,4-tetrahydroisoquinoline 2-oxide, C38H36N2O4

Abstract

Source of materialThe TIQ (Tetrahydroisoquinoline) amide, (1R,3S)-Nbenzhydryl-2-benzyl-6,7-di-methoxy-1-phenyl-1,2,3,4-tetrahydroisoquinoline-3-carboxamide (0.50 g) was dissolved in dry dichloromethane (20 mL). Potassium carbonate (2.0 equiv.) was added, and the reaction mixture was cooled to -78°C. m-CPBA (m-chloroperoxybenzoic acid, 1.2 equiv.) was then added, and the reaction was allowed to stir at -78°C for 3hours. At this time, thereactionwas warmed to room temperature. After stirring for2 hoursatroomtemperature,dichloromethane (20 mL)was added to dilute the reaction and Celite (200 mg)was added to aid filtration. The crude product was purified by columnchromatography (MeOH/DCM, 3:97; R f =0.25) to afford the product (0.25g, 50%) as aw hite solid. M.p. 180-182°C. [a] 20 =+ 100.00 (c =0 .11, CHCl 3 ). Crystals were grown in ethylacetateatroom temperature. ExperimentaldetailsAllhydrogenatoms were placed in idealised positions in riding models with U iso set at 1.2 or 1.5 times those of their parent atoms and refined with simple bond length constraints. DiscussionTetrahydroisoquinoline (TIQ)derivedcatalysts have shown to be efficientf or several asymmetric reactions [1][2][3].The title compoundisanovel chiral organocatalystcontainingaTIQ scaffold. We have recently reported the useofsimilar TIQ derivativesas organocatalysts for the asymmetric allylation of aldehydes [4]. The N-oxide orientates syn (on the sameside) to the amide hydrogen-bond donor substituent and is stabilized by an intramolecular hydrogen bond O×××H=1.85 Å. Fromthe crystal structure it is evident that the N-containing six membered ring assumesah alfchair conformation [(Q) =0 .5193(12))Å ,q=4 8.77(14)°, f = 357.37(19)°]. We have previouslyr eported similar conformationsfor TIQ based N-oxideorganocatalysts [4].