Phenylethyl isocyanate

A series of reactions was developed to transfer amines to ureido- and thioureido-derivatives for separation. The reaction of ureido-derivatives is widely used by the reaction with 1-phenylethyl isocyanate (PEIC) [8] or the naphthyl-analogue 1-(1-naphthyl)ethyl isocyanate (NEIC) [9]. Both reactions can be used not only for chiral amines but also for alcohols and thiols. 

Phenoxy-1,2-epoxypropane, 3150 Phenyl azide, 2271 2-Phenylethyl isocyanate, 3139 Phenylhydrazine, 2373... 

Figure 3. VCD and absorption spectra in the CH stretching region (a) a-phenylethanol, 0.074 M in ecu, path length O.IO cm, (b) (+)-a-phenylethyl isocyanate, 0.087 M in CCU, sample path length 0. IS cm. The time constant was 10 s, and the resolution was 6 cm. (Reproduced with the permission of North Holland Publishing Co., from ref. S9.)...

Phenyl azide, 2264 Phenyl isocyanate, 2681 2-Phenylethyl isocyanate, 3133 Phenylhydrazine, 2366 Poly(vinyl alcohol), 0827... 

Aminoquinuclidine S-( —)-l-Phenylethyl isocyanate R-1-(1-Napthyl)ethyl isocyanate RR-( + )-O,0-Dibenzoyltartaric acid SS-( — )-0,0-Dibenzoyltartaric acid 189... 

Phenylethyl isocyanate, OCNCH(CH3)Cf,H5 (1). Available from Aldrich or Fluka. 

Pereira [38] separated enantiomers of sec.-alcohols on Carbowax 20M after their conversion into carbamates by treatment with optically pure / -(+)-N-l -phenylethyl isocyanate. This reagent is prepared from commercially available R-(+)-1 -phenylethylamine and phosgene. 3(3-Acetoxy-As-etienic acid esters [39] were used for the same purpose. 

The synthesis of optically active TIQ-1-carboxylic acids has recently been accomplished by the chemical reactions shown in Fig. 26. Carboxylic acids 99 and 100, after esterification and reaction of the methyl esters with optically active I-phenylethyl isocyanates, gave ureas 101 and 102, respectively, which were separated from their diastereoisomers by chromatography (33,218). Ureas 101 and 102, on treatment with base or on... 

Optically active cathinone has been obtained through the optical resolution of racemic norephedrine using 0,C>-dibenzoyl-D-tartaric acid (26). Each enantiomer was formylated (9) and oxidized with chromium trioxide in pyridine, and the product (13) was then deformylated by heating with 20% hydrochloric acid at 40 C (Scheme 2). Estimation of the optical purity by formation of a urea (14) with (—)-l-phenylethyl isocyanate and HPLC scrutiny, showed an optical purity exceeding 98% for each enantiomer. Cathinone as the free base racemizes and dimerizes readily in hydroxylic media, and similar behavior, at a somewhat reduced rate, is also observed for solutions of the oxalate salt sometimes used for isolation purposes. Cathinone base is fairly stable in dilute solution in nonhydroxy lie, nonpolar media. It readily decomposes during drying of the leaf, hence the desire to use fresh material for hedonistic purposes 14,27). 

Merucathinone was synthesized by Wolf and Pfander (79) from rerr-butoxycar-bonyl-L-alanine (Scheme 4). Treatment with n-butyllithium and styryllithium as before formed 20, which was deblocked with trifluoroacetic acid to give merucathinone (6), isolated as the oxalate. As assessed by treatment with (+)-l-phenylethyl isocyanate and HPLC, the optical purity of 6 was greater than 97%. Treatment of r-BOC-L-alanine with 3 equiv of phenyllithium gave ketone 21, which was deblocked as before to provide a short synthesis of cathinone (2), isolated as its hydrochloride (enantiomeric excess >95%) (19). 

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