Camphor with acetonitrile

However, only recently the acid-catalyzed reaction of the keto and cyano functional groups have been reported. In these articles the unreactivity of ketones in the Ritter reaction was noted and the search for conditions to overcome this lack of reactivity was described. The reactions of camphor 110a81, isocamphanone 110b82 and their structural analogs isofenchone 110c and 5-exo-ethyl norcamphor 110d83 with acetonitrile in the... 

In 1876 Hepp and Spiess reported that aldehydes react with nitriles under acidic conditions to yield geminal bisamides (equation 25). This process proceeds by a mechanistic pathway which is essentially two consecutive Ritter reactions. In general, ketones do not yield similar products however, Kozlov has recently obtained a low yield of the geminal bisamide from camphor and acetonitrile. High yields of analogous products from cyclopentanone and cyclohexanone have also been reported. ... 

Figure 8.43 Separation of enantiomers using complexation chromatography. A, Separation of alkyloxiranes on a 42 m x 0.2S mm I.O. open tubular column coated with 0.06 M Mn(II) bis-3-(pentafluoro-propionyl)-IR-camphorate in OV-ioi at 40 C. B, Separation of D,L-amino acids by reversed-phase liquid chromatography using a mobile phase containing 0.005 M L-histidine methyl ester and 0.0025 M copper sulfate in an ammonium acetate buffer at pH 5.5. A stepwise gradient using increasing amounts of acetonitrile was used for this separation.

The groups of Pete and Rau also employed chiral amino alcohols for the enantioselective protonation of simple enols 23a-c that were photochemically generated from 2-/-butyl indanones and tetralones 22a-c by a Norrish type II photoelimination (Scheme 9) [41,42]. Best enantioselectivities were obtained at — 40°C in acetonitrile with 0.1 equivalent of the chiral amino alcohol. In the case of indanone 22a, the selectivity reached 49% ee with (— )-ephedrine ent-18) and could not be further enhanced by the camphor derived inductor 20. With this amino alcohol, enantioselectivities over 80% ee were induced in the case of tetralone 22b. A benzyl substituent in place of the methyl group led to substantial decrease of the selectivity to 47% ee. Linear ketones gave low yields and enantioselectivities around 9% ee. 

Catalytic amounts of camphor-10-sulfonic acid (CSA) in methanol and dichloro-methane smoothly cleave the orthoester function in 23, giving the intermediate y-lactone-l,3-diol. Subsequent protection of the primary alcohol function with di-methylphenylchlorosilane (TPSCl) in dimethylformamide with imidazole as the base and of the secondary alcohol function via alcoholate with benzylbromide (BnBr) following WiLLlAMSON s ether synthesis yields the y-lactone 24. Its reduction with lithiumaluminumhydride leads to two vicinal primary alcohol groups. Thereafter, camphor-10-sulfonic acid (CSA) in dichloromethane selectively cleaves the TBS ether and catalyzes the transketalization with acetone dimethyUcetal to the precursor 25 of the aldehyde 8. Smooth oxidation of the primary alcohol function in 25 is achieved with tetrapropylammoniumperruthenate (TPAP) and A-methyl-morpholine-A-oxide (NMO) in acetonitrile. 

The best results were obtained with 20 mol% camphor-derived sulfonium salt 230, with 1.5 equivalents of 3-phenylallyl bromide and one equivalent of chalcone at 0°C in a mixture of fert-butyl alcohol and acetonitrile (2.5 1). The cyclopropanation product was obtained in moderate diastereoselectivity (86/14), good enantiose-lectivity (82% ee) and in high yield (92%). The method could be extended to a variety of a,P-unsaturated carbonyl compounds (Table 7.16). The chiral sulfide 228 could also be employed directly without preformation of the sulfonium salt 230 with similar results. 

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