Staudinger reaction amine 53 preparation

Trifluoroalanine has also been prepared by reducing trifluoropyruvate imines (ethyl trifluoropyruvate is available commercially it is prepared either from per-fluoropropene oxide or by trifluoromethylation of ethyl or f-butyl oxalate). These imines are obtained by dehydration of the corresponding aminals or by Staudinger reaction. They can also be obtained by palladium-catalyzed carbonylation of trifluoroacetamidoyl iodide, an easily accessible compound (cf. Chapter 3) (Figure 5.4). Reduction of the imines affords protected trifluoroalanines. When the imine is derived from a-phenyl ethyl amine, an intramolecular hydride transfer affords the regioisomer imine, which can further be hydrolyzed into trifluoroalanine. ... 

Staudinger reaction),615 H2 and a catalyst, Mg or Ca in MeOH,616 N2H4-Pd,617 and tin complexes prepared from SnCl2 or Sn(SR)2.6l i This reaction, combined with RX — RN3 (0-61). is an important way of converting alkyl halides RX to primary amines RNH, in some cases the two procedures have been combined into one laboratory step.61 Sulfonyl azides RS02N, have been reduced to sulfonamides RSO NH2 by irradiation in isopropyl alcohol620 and with NaH.621... 

An alternative route starting from serine 73 or threonine 68 74 makes use of diethoxy-triphenylphosphorane. Attempts to asymmetrically synthesize (25)-aziridine-2-carboxylic acid (1) by treating a, 3-dibromopropanoates with chiral amines 75 or by the Staudinger reaction from oxirane-2-carboxylic acid ester 70,76 leads to optically impure products, whereas 3-alkyl derivatives of tert-butyl aziridine-2-carboxylates can be prepared with high cis-selectivity from a-halo ester enolates and jV-trimethylsilyl imines. 77 Moreover, when optically... 

Azides may be converted to amines by hydrogenation, but another possibility is the Staudinger Reaction, which is a very mild azide reduction. As there are a variety of methods for preparing azides readily, the Staudinger Reaction makes it possible to use "N3 as an" NH2 synthon. 

The research team of J. Tadanier prepared a series of C8-modified 3-deoxy-P-D-manno-2-octulosonic acid analogues as potential inhibitors of CMP-Kdo synthetase. One of the derivatives was prepared from a functionalized olefinic carbohydrate substrate by means of the Wohl-Ziegler bromination. The stereochemistry of the double bond was (Z), however, under the reaction conditions a cis-trans isomerization took place in addition to the bromination at the allylic position (no yield was reported for this step). It is worth noting that the authors did not use a radical initiator for this transformation, the reaction mixture was simply irradiated with a 150W flood lamp. Subsequently the allylic bromide was converted to an allylic azide, which was then subjected to the Staudinger reaction to obtain the corresponding allylic amine. 

The addition of an acid chloride to an imine is an important method for the preparation of (3-lactams and is often referred to as the Staudinger reaction. The reaction allows a convenient and mild approach to the -lactam antibiotics and has therefore received considerable attention. Good stereoselectivity in favour of the cis 3,4-disubstituted product is common. For example, the p-lactam 182 was formed in reasonable yield by condensation of the acid chloride 180 and the imine 181 (3.120). The reaction is not thought to be a concerted cycloaddition with the ketene, but to take place via a zwitterionic intermediate. Almost complete asymmetric induction in the synthesis of -lactams by the Staudinger reaction using a chiral auxiliary or a chiral tertiary amine, such as benzoylquinine, has been reported. 

The Staudinger reaction has also been employed for synthetic purposes other than the preparation of iminophosphoranes. Thus, reactions between appropriate k -phosphorus azides and phosphines gave the amine functionalized dendron (68) that could be grafted onto a tetraphosphorus macrocycle with four pendant P-N=P(C6H5)2(p-C6H4-CHO) groups in order to obtain the expected topologicaly amplified compound as a mixture of diastereoisomers. ... 

Staudinger and Kupfer2 discovered a very interesting method for the preparation of diazomethane. They observed that when the isonitrile reaction of primary amines was applied to hydrazine, diazomethane,3 and not the expected di-isocyanogen, C=N—N=C, was produced in the manner indicated in the following equations ... 

Acetal polymers are formed from the polymerization of formaldehyde. They are also given the name polyoxymethylenes (POMs). Polymers prepared from formaldehyde were studied by Staudinger in the 1920s, but thermally stable materials were not introduced until the 1950s, when DuPont developed Dehin. Hompolymers are prepared from very pure formaldehyde by anionic polymerization as shown in Fig. 2.1. Amines and the soluble salts of alkali metals catalyze the reaction. The polymer formed is insoluble and is removed as the reaction proceeds. Thermal degradation of the acetal resin occurs by unzipping with the release of formaldehyde. The thermal stability of the polymer is increased by esterification of the hydroxyl ends with acetic anhydride. An alternative method to improve the thermal stabihty is copolymerization with a second monomer, such as ethylene oxide. The copolymer is prepared by cationic methods developed by Celanese and mar-... 

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