foam the product was washed repeatedly with et 2 o and concentrated in vacuo the white solid was dried in vacuo at 40 u00b0 c for one hour to give r 2 6 bis 1 methylethyl phenyl carbamic acid 2 amino 2 phenylethyl ester to a 50 ml 3 neck flask equipped with a magnetic stirrer were added the ester obtained above 507 mg 1 3 mmole 10 ml thf and 407 mg 4 mmole triethylamine 652 mg 2 7 mmole of heptanoic anhydride was added in one portion under a n 2 atmosphere and stirred for two hours the mixture was diluted with ethyl acetate 10 ml and filtered the filtrate was washed with 1n hcl 1n naoh and brine the solution was dried over mgso 4 filtered and stripped to dryness to give r 2 6 bis 1 methylethyl phenyl carbamic acid 2 1 oxoheptyl amino ethyl ester m p 170 u00b0 172 u00b0 c when in the procedure oi example 2 an appropriate amount of s u03b1 phenylglycinol is substituted for r 31 u03b1 phenylglycinol s 2 6 bis 1 methylethyl phenyl carbamic acid 2 1 oxoheptyl amino 2 phenylethyl ester is obtained to 2 0 g 5 3 mmole of s 2 6 bis 1 methylethyl phenyl carbamic acid 2 amino 2 phenylethyl ester dissolved in 40 ml dmf was added 0 5 g 12 5 mmole sodium hydride 60 dispersion to this was then added 1 42 g 5 8 mmole 1 6 dibromohexane in one portion the reaction was stirred at room temperature for one hour then quenched with water and the product extracted with et 2 o the organic solution was dried over mgso 4 filtered and concentrated to dryness the oil was chromatographed on silica gel eluting with hexane ethyl.