and the filtrate is evaporated to dryness the residue is dissolved in 250ml ethyl acetate and washed consecutively with water hcl 0 05n d 2 co 3 solution 5 and nacl solution 30 after drying over na 2 so 4 the filtrate is evaporated to dryness and the residue is crystallized from ether petroleum ether yield 19 3g melting point 108 110 u00b0 c b h ala ala ome hcl 18 75g boc ala ala ome from a is dissolved in 150ml methylene chloride and hcl is passed into the solution for 45 minutes under constant cooling in iced water yield of deprotected product 14 3g ala c boc met ala ala ome 15 8g boc met n 2 h 3 dissolved in 150ml dmf is activated at 20 u00b0 c with 28 0ml 4 2n hcl in thf and 8 10ml iso amyl nitrite after activating for 20 minutes at 15 u00b0 c the solution is neutralized with 14 5ml nem after which a solution of 14 3g h ala ala ome hcl from b in 75ml dmf and leq nem is added after the ph has been adjusted to 7 2 with nem the reaction mixture is kept for 48 hours at about 4 u00b0 c after 48 hours the nem hcl is filtered off and the.