Hello I have a question concerning the rotary evaporator, how can I know what temperature should be used ?
Here are my 2 experiments,
1) but I don't know what temperature should be used during the concentration under reduced pressure
2) Also I don't know what does it mean 1.1 equivalents for the part one that I have 4g * 1.1 as Cbz-beta-Ala-OH ?
3) I wrote the mechanism of the part 2 but I am not sure if it is correct, please correct me if I am wrong.
PART 1: Cbz-beta-Ala-OH
To a solution cooled to -10°C of Cbz-beta-Ala-OH (4g) in pyridine (26,9mL) and tertio-bulanol (44,8ml) in a 100 ml anhydrous two-necked um pallion, is added phosphoryl chloride POCl3 (1.1 eq) using reduce syringe. The mixture is stirred for 15 minutes at -10 C.
Follow the reaction on CCM. The solvents are evaporated and to the residue is added water (45 ml). This phase aqueous is extracted with ACOET (3 times 25 ml). The organic phases are combined and washed successively with a saturated solution of Na2CO3 (30ml), water (30ml), KHSO4(30ml), 2M and brine. The organic phase is dried (Na2SO4), filtered and then concentrated under reduced pressure. The residue is purified by chromatography on silica gel (about 80g).
PART 2 : H-beta-Ala-OtBu-OEt
To a solution of ethyl bromoacetate (1 eq.) in anhydrous THF (5 ml/mmol) is slowly added a solution of H-beta-Ala-OtBu (1 eq.) and N-methyl morpholine (NMM, 1.1 eq.) in anhydrous THF (1
mI/mmol). The reaction is followed on TLC. At the end of the reaction, the solvent is evaporated and is replaced by ether (same volume). The suspension is filtered and the residue is concentrated under vacuum. The latter is purified by silica gel chromatography. Determine the eluent (Rf0.2 by a mixture of ether and hexane).
