Extra Functional Groups Research Articles

N‐phosphoryl amino acids and peptides. Part II: Fast atom bombardment mass spectrometry of N‐di‐isopropyloxyphosphoryl and N‐dibutyloxyphosphoryl amino acids

AbstractThe positive ion fast atom bombardment mass spectra of N‐di‐isopropyloxyphosphoryl (Dipp) and N‐dibutyloxyphosphoryl (Dbp) amino acids or amino acid methyl esters are presented; and according to the observation of the metastable ions and the high‐resolution accurate mass measurement their fragmentation patterns are postulated. Both types of compounds were found to undergo similar fragmentations to produce (HO)2P(O)NCHR + H+, in most cases as the most abundant fragment ion of structural significance. An intrinsical difference between the two types of compounds is that N‐Dippamino acids appear to favour the successive losses of two molecules of propylene, while the loss of HCOOH seems to be preferred by the Dbp amino acids. For those compounds containing an extra functional group on the side chain of amino acids such as serine or glutamic acid some other type of fragmentation was observed besides the normal phenomenon.

Preparation of polymer-supported amino acid

Insoluble polymer-supported amino acids have been synthesized by simple one-pot synthesis. Amino acids were solubilized in organic solvent by trimethylsilylation. Solubilized amino acids (L-Tyr, L-Ser, D-HPG, L-Cys) having functional groups such as OH or SH were easily attached to crosslinked polystyrene beads through benzyl ether or thioether linkage. Other amino acids without extra functional groups could be attached to the polymer through benzyl amine linkage.

New trigonal lattice hosts: stoicheiometric crystal inclusions of laterally trisubstituted benzenes—X-ray crystal structure of 1,3,5-tris-(4-carboxyphenyl)benzene·dimethylformamide

New host molecules with a central 1,3,5-trisubstituted benzene ring and rigidly attached lateral arms composed of aryl or arylethynyl and extra functional groups are reported. They are shown to give more than thirty clathrates with a wide variety of organic solvents comprising alicyclic, aromatic, heterocyclic, dipolar aprotic, and protic molecules. Inclusion selectivities and stoicheiometries of the different clathrates are discussed. The crystal structure of (2a)·dimethylformamide (DMF)(1:3) inclusion compound has been determined from single-crystal X-ray diffraction. The crystals show R symmetry. There are six host and eighteen guest molecules in the hexagonal unit cell with a=b= 23.160(9) and c= 11.812(3)A. The final linear R is 0.082 for 1 518 unique reflections. The host molecules adopts a propeller conformation with perfect three-fold symmetry and acts as a donor in hydrogen bonds to three DMF molecules. In the crystal structure the host–guest units are arranged stack-wise.