Serine Experimental Procedure

The reaction of acceptor-substituted carbene complexes with alcohols to yield ethers is a valuable alternative to other etherification reactions [1152,1209-1211], This reaction generally proceeds faster than cyclopropanation [1176], As in other transformations with electrophilic carbene complexes, the reaction conditions are mild and well-suited to base- or acid-sensitive substrates [1212], As an illustrative example, Experimental Procedure 4.2.4 describes the carbene-mediated etherification of a serine derivative. This type of substrate is very difficult to etherify under basic conditions (e.g. NaH, alkyl halide [1213]), because of an intramolecular hydrogen-bond between the nitrogen-bound hydrogen and the hydroxy group. Further, upon treatment with bases serine ethers readily eliminate alkoxide to give acrylates. With the aid of electrophilic carbene complexes, however, acceptable yields of 0-alkylated serine derivatives can be obtained. 

Experimental Procedure 4.2.4. Etherification of a Serine Derivative by Intermo-lecular O-H Insertion Methyl (25)-3-[(Ethoxycarbonyl)methoxy]-2-(benzyloxy-carbonylamino)propanoate... 

Phospholipase A2 Action. Incubation of phosphatidylserine with phospholipase A2 obtained from Crotalus adamanteus or Naja Naja snake venom will show that the serine-containing phosphoglyceride was smoothly and completely converted to a lysophosphatidylserine with liberation of 1 mol of fatty acid per mole of lipid P. The experimental procedure was the same as the one described before in this and in the previous chapter. The products of the reaction can be recovered by thin-layer chromatography on Whatman K6 plates in a solvent system of chloroform-acetone-methanol-acetic acid-water (4.5 2 1 1.3 0.5, v/v). 

Procedure Generate serine octamer ions in the ESI ion source mass-select ion of interest -> inject package of ions into the drift tube detect ions exiting the drift tube and record their arrival time distribution calculate collision cross-section compare experimental cross-section with theoretical ones calculated for putative structures. 

---