Schmidt reactions Subject

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. 

In a specific case it has been possible to achieve isomerization at the C-15 to C-20 junction. Dehydration of yohimbic acid gives apoyohimbic acid (XVIb) which on subjection to the Schmidt reaction yields the ketone, ( +)-16-yohimbone (XVII) (10,11). When the same series of reactions is applied to 3-epi-a-yohimbine (XVIII), there is first generated the ketone XIX which spontaneously epimerized to XX which is ( — )-16-yohimbone (12). 

The N-acyl and N-alkyl derivatives of aminoarylarsinic acids are prepared by the usual methods. Acetyl-jp-aminophenylarsinic acid, in addition to the usual method of acetylation of the arsinic acid, may be formed by subjecting p-aminoacetanilide to the Bart-Schmidt reaction. An interesting series of N-aryl derivatives of p-aminophenylarsinic acid has been obtained by King and his co-workers in the course of seeking organic arsenicals of therapeutic value. ... 

After consideration of the mechanism of the Schmidt reaction of carboxylic acids (cf. section III.A)the prediction was made and verified that the Curtins rearrangement would be subject to acid catalysis The charge and bond distribution in the substrate can almost certainly be best represented by 1 and protonation (reaction 7) was believed to form 2 in which the positive charge on the nitrogen of the... 

Amino-3-hydroxy-l 4-benzisoxazine hydrochloride (12 grams), when subjected to the Bart-Schmidt reaction, yields 1 25 grams of the stibinic acid as a light brown amorphous powder, insoluble in water and the usual solvents, but readily soluble in dilute alkali solutions. 

Use of carbocations to initiate the Schmidt reaction has been the subject of several investigations during the last two decades. The cationic intermediate can be generated from secondary or tertiary alcohols or from olefins. The first example was described by the Pearson group for the synthesis of a bicyclic enamine. However, various drawbacks still remain when carbocations are involved limited stability of the intermediates, low selectivity, and the need... 

Phthalide and phenolphthalein appear to be the only lactones which have been subjected to the Schmidt reaction, and both proved to be unreactive. Acetic anhydride gives a yield of 85% of methyl amine. Phthalic anhydride yields isatoic anhydride, benzimidazolone, and an-thranilic acid. ... 

An attractive method for determining carboxyl groups is based on the Schmidt reaction, in which the carboxyl group is subjected to reaction with sodium azide in sulfuric acid [38]. The acylazide formed rearranges to an amine, with the liberation of nitrogen and carbon dioxide ... 

The second reaction we will treat here that in many cases proceeds by a homogeneous mechanism is the solid-state polymerization of diacetylenes. The photolability of these compounds has long been known (189), but it was not until the appearance of the pioneering works of Hirshfeld and Schmidt (168) and of Wegner (190) that some real understanding of the process was introduced. This led to an explosive interest in the subject, and more than 200 diacetylene derivatives have now been studied, by a wide variety of techniques (191). 

Cognitive effects The effects of LI 160 on cognitive performance of subjects being treated for depression were examined. A significant antidepressant effect was seen and with low incidence of side effects, but no adverse cognitive effects were found on measures of attention, concentration, or reaction time (Schmidt and Sommer 1993). 

It is well established, in a qualitative sense, that chemical reactions occurring in crystals are subject to restrictive forces, not found in solution, which limit the allowable range of atomic and molecular motions along the reaction coordinate. This often leads to differences, either in the product structures or the product ratios, in going from solution to the solid state. This was first demonstrated in a systematic way by Cohen and Schmidt in 1964 in their studies on the solid state photodimerization of cinnamic acid and its derivatives (1 ). This work led to the formulation of the famous topochemical principle which states, in... 

N-Dienv11richIoroacetamide 174 (11 = 0, R=H) was, however, subsequently also subject to tandem RCM/ATRC catalyzed by the Grubbs II catalyst 175 (Fig. 43) [254]. The yield of 177 in this reaction was reported to be 82-91%, showing that catalyst 175 is also effective in such tandem processes. Tandem cross-metathesis/ ATRC reactions of N- a 11 v 11 ri c h I o ro acetamides with styrenes catalyzed by 175 produced rather low yields of trichlorinated lactams [254]. Almost at the same time Schmidt and Pohler reported similar tandem RCM/ATRC sequences of 1,6-dienyl trichloroacetates with 5 mol% of 175 and of 1,7-dienyl trichloroacetates... 

For more details on this subject, see Barrere, Jaumotte, Fraeijs de Veubeke Vandenkerckhove Raketenantriebe. Elsevier, Amsterdam, 1961. Also Dadieu, Damm, Schmidt Raketentreibstoffe Springer, Wien 1968 also -> Gas Jet Velocity and -> Thermodynamic Calculation of Decomposition Reactions. 

Schmidt and coworkers [269] tested the pharmacodynamic interaction of Hypericum and alcohol. They included 32 healthy young volunteers of both sexes in a cross-over trial. In a randomized sequence, the subjects received 3 x 300 mg/day of the Hypericum extract LI 160 for 7 days and placebo for another 7 days. On day 7 and day 14 they underwent different tests of reaction time and psychomotor function after oral intake of individually calculated amounts of alcohol resulting in blood concentrations between 45 and 80 ml/1. 

When I was young, solid-state phase changes and chemical reactions were regarded more as a nuisance than as an area worthy of serious study and attention. It was the topochemical approach to solid-state chemical reactions, pioneered by Gerhard Schmidt, that transformed the subject for me and for many others. The textbook example is the photochemical dimerization of (fj-cinnamic acids in solution such compounds yield mixtures of the various possible stereoisomeric products, but irradiation of a particular crystal leads to a single product, or to no reaction, depending on the crystal structure [40]. Thus, one can determine the relative positions of the atoms before the reaction and after it, and haice deduce the metrical relationships that needed to be satisfied for reaction to proceed. In the meantime we have learned that not all chemical reactions in solids are topochemical. Some proceed not in the ordered bulk of the crystal but at defects, on the surface, or at other irregularities. 

Humberston et al. 2003 Musch et al. 2006 Russmann et al. 2003 Sass et al. 2001 Schmidt et al. 2005 Stoller 2000). These reports have been subject to critical analysis by a number of organizations and individuals (Schmidt 2007 Schmidt et al. 2005 TMEC 2002 Waller 2002). A review of liver toxicity cases indicated that the reported cases represented unpredictable reactions, and that cases were best characterized as idiosyncratic reactions of the metabolic type (Teschke et al. 2008). Of 82 cases of liver toxicity reported through 2002, one case was assessed as being "certain" or "probable" by multiple reviewers, with up to 12 others being noted as "probable" (BfArM 2002 Schmidt 2007)... 

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