Boyer reaction

The Boyer reaction - a relative of the Schmidt process - involves 2-oxazoline formation from a 2-azidoethanol and an aldehyde (RCHO).282 Using a 2-aryl-2-azidoethanol, a 2-oxazoline product and its 3-isomer are obtained using BF3 catalysis. However, on using copper(II) triflate, an acetal, RCH[OCH2CH(Ph)N3]2, resulted. 

Oxazolines can also be prepared via a Boyer reaction between aliphatic aldehydes and 2-aryl-2-azidoethanol <20050L4145>. As in the earlier example, the 3-oxazoline product 271 was formed along with the generation of isomeric 2-oxazolines. An enantiomerically pure azido alcohol 272 can be used to induce the absolute stereochemistry of the oxazoline product (Scheme 79). The product oxazolines, for example 273, were formed with modest to good ees, albeit in low yields. 

Wannlund, J., DeLuca, M., Stempel, K., and Boyer, P. D. (1978). Use of 14C-carboxyl-luciferin in determining the mechanism of the firefly luciferase catalyzed reactions. Biochem. Biophys. Res. Commun. 81 987-992. 

The most interesting TV-coupling reaction of this subsection is that with azide ions, which has been known since the end of the last century. This reaction is frequently used for the preparation of aryl azides. Two examples can be found in Organic Syntheses (Smith and Boyer, 1963 Mendenhall and Smith, 1973). As Scheme 6-20... 

Bohan, A., Boyer, J. L., Mechanism of hepatic transport of drugs implications for cholestatic drug reactions, Semin. Liv. Dis. 2002, 22, 123-136. 

For a commercial database of known metabolic transformations, Borodina et al. [76] extracted all known sites of aromatic hydroxylations. These observed transformations were used to generate all possible transformations for each molecule, giving an estimate of the probability that each transformation would actually occur. The method was 85% accurate in predicting site of aromatic hydroxylation when tested against a second metabolism database containing 1552 molecules. Boyer et al. [77] took a similar approach using reaction center fingerprints to estimate the occurrence ratio of a particular metabolic transformation. The method successfully predicted the three most probable sites of metabolism in 87% of compounds tested. 

J. H. Boyer, in The Chemistry of the Nitro and Nitroso Groups, Part 1, Organic Nitro Chemistry Series, Ed. H. Feuer, Wiley-Interscience, New York, Methods of Formation of the Nitroso Group and Its Reactions , Chapter 5, 215-300 (1969). 

Boyer and co-workers" also reported the synthesis of the guanidine tricycle (122), prepared as the tetrahydrochloride salt from the condensation of two equivalents of guanidine with 1,4-diformyl-2,3,5,6-tetrahydroxypiperazine in concentrated hydrochloric acid. Treatment of the tricycle (122) with absolute nitric acid yields thebis-nitrimine (123), whereas the same reaction with nitric acid-acetic anhydride yields HHTDD (117). 

Boyer and Gunasekaren reported the synthesis of the furazan-based heterocycle NOTO (44), which contains 50 % by mass of nitrogen and is a liquid at room temperature. The flve-step synthesis of NOTO (44) starts from the diazotization of 4,4 -diamino-3,3 -azoxyfurazan (DAAF) (27), followed by reaction with sodium azide to form the diazide (42). Heating the diazide (42) as a solution in acetonitrile induces cyclization to the triazole (43) and this is followed by reduction and oxidation of the remaining azide group to complete the synthesis of NOTO (44). 

The now classical example is lactate dehydrogenase. Sil-verstein and Boyer were the first to determine the rates of exchange between cognate pairs of reactants ie., lactate and pyruvate as well as NAD and NADH). Convenient [NADH]/[NAD ] and [pyruvate]/[lactate] ratios were chosen such that when combined they satisfied the apparent equilibrium constant for the LDH reaction. These investigators first established that each exchange rate was directly proportional to the duration of exchange and likewise directly proportional to enzyme concentration. As an additional control, they also demonstrated the equality of the pyruvate lactate exchange... 

Metastable cyanomethylnitrolic acid and its red color in basic water solution have already been observed by Steinkopf. Moreover, he postulated the existence of the silver salt AgNNtCM. The intermediate formation of the silver salt has also been postulated by Pillai and Boyer in the reaction of ICH2CN with AgN02 which finally gave NC—CH2—O—N=C(N02)CN, the only product which could be isolated . 

Boyer, Peter J. Big Guns. The New Yorker, vol. 75, May 17, 1999, pp. 54ff. Describes the efforts of Dennis Flenigan and the Castano group of lawyers who, fresh from their victory over Big Tabacco, are organizing the legal assault on the firearms industry. They believe that public reaction to the Littleton, Colorado, shootings may aid their cause considerably. 

P. George and J. Griffith, in Enzymes, P. D. Boyer, H. Lardy and K. Myrback, eds., Vol. 1, p. 347, Academic Press, New York (1959). The first quantitative formulation of vibrational activation for redox reactions from first-layer ligands. 

The same reaction also occurs at a lower temperature. 0.665 % of the substance decomposed at 20°C to form benzotrifuroxane in 3 years 2.43% at 35°C in one year 0.65% at 50°C in 10 days and at 100°C the substance underwent complete change in 14 hr. This decomposition is not, however, autocatalytic. This reaction — the formation of furoxane derivatives from aromatic azides with nitro group in the or/Ao-position — is of a general character (Boyer al. [160]). Despite the ease with which it decomposes trinitrotriazidobenzene has not been rejected for use as an initiator. In some countries large scale experiments are in progress to examine the possibilities of developing its practical application. 

An extensive review of the chemistry of aliphatic and aromatic azides is given by Boyer and Canter [167] and Gray [168]. Organic azides are subject to various reactions such as the Bergmann degradation and the synthesis of peptides, the well known Curtius rearrangement, the Darapsky synthesis of a-aminoacids [169], for synthesis of triazoles [170], tetrazoles ( Schmidt reaction ) [169] and [171] etc. These reactions lie beyond the scope of the present book. 

Denson (Ref 9) on those a-azidoalkylidenimines which undergo cyclic isomerizations to tet-razoles and Boyer Canter (Ref 15) made a thorough survey of the available information on alkyl and aryl azides. Cirulis Straumanis (Ref 6) prepd a number of new azides of org bases bur none of these azides showed eiqjl props. Schaad (Ref 14) obtd a patent for the manuf of esters of hydrazoic acid based on the reaction of alkenes, cyclic olefins, ary 1-alkenes cycloalkylalkenes with HN3 in the presence of an acid catalyst... 

On the basis of detailed kinetic and binding studies of the reactions catalyzed by F0Fi, Paul Boyer proposed a rotational catalysis mechanism in which the three active sites of F take turns catalyzing ATP synthesis... 

Kim, P. S. and Baldwin, R. L. 1982. Specific intermediates in the folding reactions of small proteins and the mechanism of protein folding. In Annual Review of Biochemistry, Vol. 51. E.S. Snell, P. D. Boyer, A. Meister and C.C. Richardson (Editors). Annual Reviews, Palo Alto, Calif., pp. 459-489. 

Figure 9-7 (A) Effect of glucose and glucose 6-phosphate concentrations on reaction rate of yeast hexokinase at equilibrium. Reaction mixtures contain 1-2.2 mM ATP, and 25.6 mM ADP at pH 6.5. From Fromm et al.51 (B) Effect of lactate and pyruvate concentrations on equilibrium reaction rates of rabbit muscle lactate dehydrogenase. Reaction mixtures contained 1.7 mM NAD+, and 30 - 46 pM NADH in Tris-nitrate buffer, pH 7.9, 25°C. From Silverstein and Boyer.53...

Recent experiments with [180]PS and E. coli enzyme by Stokes and Boyer (89) and Balakrishnan et al. (90) show that transfer of oxygens from Pj to glutamine is the most rapid of the measured isotopic exchanges. The reaction for net formation of ATP follows. 

---