R -1- 1-Naphthyl ethyl Isocyanate

Nonracemic NEA is equally useful in preparing diastereomeric carbamates. Typically, the carbamates are derived from alcohols and (R)-(+)-naphthylethyl isocyanate, which is conveniently prepared from (R)-(+)-NEA (see (R)-1-(1-Naphthyl)ethyl Isocyanate). However, the diastereomeric carbamates may also be... 

R-(-)-1 -(1 -Naphthyl)ethyl isocyanate (Ega Chemie, Steinheim, Germany)... 

Sample preparation Reflux 1.23 g fluoxetine with 788 mg (R)-(-)-l-(l-naphthyl)ethyl isocyanate in 25 mL toluene for 2 h, evaporate to diyness under reduced pressure, reconstitute, iiyect an aliquot. 

Column 100 X 4.6 3 p,m (R)-(-)-(l-naphthyl)ethylurea (Prepare by pumping 2 g (R)-(-)-l-(l-naphthyl)ethyl isocyanate in 100 mL dichloromethane through a 100 X 4.6 3 pm ami-nopropyl-silanized silica column (Regis) at 2 mL/min (without detector), after 12.5 min recycle the mobile phase, after 2 h wash the column with 300 mL dichloromethane at 2 mL/min, wash with hexane isopropanol 80 20 until a steady baseline is achieved.) Mobile phase Hexane isopropanol 87.5 12.5 Flow rate 1.5 Detector UV 235... 

Silica gel HPTLC plates were used with the following chiral reagents and analytes 7 -(-)-l-(l-naphthyl)ethyl isocyanate for six / ,5-)8-blocking agents with benzene/ethyl ether/acetone (88 10 5) mobile phase and UV absorption and fluorescence detection (Rf differences 0.05-0.09) [48] (/ )-(- -)-1-phenylalanine hydrochloride for ketoprofen, suprofen, and indoprofen with benzene/methanol (93 7) and chloroform/ethyl acetate (15 1) mobile phases andUV (254 nm) detection (R differences were 0.04-0.10, with the i -isomer migrating more slowly for each compound) [49] and (5)-(- -)-naproxen chloride for the methyl esters of 10 amino acids with toluene/dichloromethane/tetrahydrofiiran (5 1 2) mobile phase and UV detection (Rf differences 0.04-0.10, with the i -isomer always having a lower value than the 5-isomer) [50]. 

Recently, poly(vinyl alcohol)-isocyanate reactions have been run successfully in dimethylsulfoxide solutions by several lab- oratories, including ours. While there are reports of solvent derived products from the reactions of isocyanates in DMSO (60), these reactions do not seem to pose a problem in the reaction with poly(vinyl alcohol). This solvent has been used to react PVA with methoxymethyl isocyanate (61.62) and a series of isocyanates including methyl, ethyl, isopropyl, phenyl and 1-naphthyl (63). This reaction is illustrated in Equation 17 where R is... 

Typical procedure. l-Methyl-d-cyanobutyl N-[l-(l-naphthyl)ethyl]carbamates 614 (R = Me, n = 4) [439]. Procedure A A stirred solution of 5-cyanopentan-2-ol (8.0 g, 70.8 mmol), (R)-( —)-l-(l-naphthyl)ethyl isocyanate (13.9 g, 70.8 mmol), dry benzene (150 mL), and two drops of dimethylethanolamine catalyst was heated at reflux under N2 for 24 h. The solvent was then removed in vacuo, and the crude diastereomeric carbamates were completely separated by chromatography (on acidic alumina, eluting with CHCla/hexane, 2 1) using an automated preparative LC system. A total of 8.9 g (81%) of the high R( (R,R) diastereomer was collected as a yellow viscous oil. 

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