Intermediate (VII) was coupled with beta-alanine benzyl ester (VIII) to give amide (IX). After hydrogenolysis of the benzyl ester of (IX), the acetate esters were removed by treatment with ammonia in MeOH, THF.
Phenylsulfanyl glycoside (I) was coupled with serine derivative (II) in the presence of N-bromosuccinimide, iodine and tetrabutylammonium triflate yielding the serine glycoside (III). Reductive cleavage of the trichloroethoxy carbonyl group of (III) with Zn and HOAc afforded amine (IV), which was acylated with (R)-3-(tetradecanoyloxy)tetradecanoic acid (V) using DCC and HOBt. Hydrogenolysis of the benzyl ester (VI) over palladium black provided carboxylic acid (VII).