From Aminoacids

Particularly interesting are the results obtained with the phosphonium ylides including an acyl rest derived from aminoacid if the N-H bond reactivity is blocked by an amide protection, the alkyne formation takes place [25,27], but if the N-H bond is not deactivated, an intramolecular cyclization occurs to give a new stabilized ylide [27,28]. 

Chiral bicyclic guanidinium receptors (e.g. 12-14, S,S-configuration shown) have been developed in our group from aminoacid precursors [16]. Improved synthetic procedures for such compounds were later reported by Schmidtchen [17] (who in 1980 presented a first type of achiral bicycloguanidinium hosts [18] that form complexes with several oxoanions [19]). Most derivatives are highly... 

The study of alkaloids of the Erythrina genus is of assistance in grouping species, but only some of the species have been carefully examined [375]. Alkaloids are compounds, generally with heterocyclic nitrogen in the molecule, biosynthesized as from aminoacids. 

From Aminoacids - The synthesis of a constituent amino-sugar of calichea-micin by asymmetric allylboronation of an L-serinal derivative (Vol. 29, p. 131) has been reviewed. (+)-Elsaminose 39, a constituent of the antibiotic elsamicin A, was synthesized from the L-threonine-derived D-thneose derivative 38 (Scheme 10). ... 

As for photochemistry, aliphatic amines are photodegraded over titanium dioxide, and the nitrogen is found mainly as ammonium cation. The complex issue of H elimination from aminoacids has been confronted by experiments and computation, a recent example referring to phenylalanine and derivatives. A detailed mechanistic analysis of the H loss from aniline... 

A nice example of photochemical synthesis has been reported for the case of p-lactams. Thus, a-diazoketones prepared from aminoacids by diazotransfer are decomposed under irradiation and undergo an intramolecular Wolff rearrangement to give a p-lactam. This occurs with complete retention of the configuration and indeed the enantiomerically pure diazoketones prepared from natural aminoacids give likewise pure p-lactams (see... 

The polyamide from 9-aminononanoic acid was then made and found to have a too low melting point of 195°C but fiber properties comparable to silk. This lead initiated extensive studies on polymers from aminoacids or diamines and dibasic acids. On February 28, 1935, the superpolymer from hexamethylenediamine and adipic acid was first made. Its properties and melting point over 260°C, safely higher than ironing temperature, labeled it as the logical fiber candidate. Many a talent would have to be called on, however, for the difficult, unchartered course from laboratory to commercial manufacture of the first synthetic fiber [11,123. Some of the problems are shown in Table MK-2 together with the time and effort to overcome them. 

Electrostatic Differential Transition State Stabilization energies resulting from aminoacid... 

From Aminoacids. - Syntheses of aminosugars from serine and threonine have been reviewed. Dondoni and co-workers used their thiazole chain extension methodology to prepare L-nojirimycin 46 and L-mannonojirimycin 47 from the L-serine derived aldehyde 44 (Scheme 12). As well, they reported alternative routes to 45,46 and 47 and an improved synthesis of the protected methyl glycosides of the 3-deoxy-analogues of 46 and 47 (cf. Vol.24, p.llS), all from 44. They have also devel( )ed an improved method to convert various carbohydrate thiazole derivatives to the corresponding aldehydes (with i,MeOTf ii,NaBH4 and iii,Cu<32 CuO) in yields of 70-85%. The... 

Apart from aminoacids, peptides and proteins, many other metalbinding substances play essential roles in all living cells. Firstly, there are the pteridines (including folic acid) and purines, whose stability constants have been determined (Albert, 1953 Albert and Serjeant, 1960).Riboflavine is most avid in the partly reduced state (Hemmerich, Veeger and Wood, 1965). Spermine (//. ), and the simpler diamines such as spermidine and cadaverine, are widely distributed metal-binders. 

---