Carbonyl reagents and

Boron-bonded p -borazine complexes of transition metals have been prepared by two different approaches (a) nucleophilic substitution of B,fi, fi"-trichloro-borazine with an anionic metal carbonyl reagent and (b) oxidative addition of a B-Br bond of 5,5, B"-tribromoborazine to a zerovalent group 10 complex (see examples in Scheme 9.2). 

Streptomycin B was inactivated by carbonyl reagents. On catalytic hydrogenation it absorbed one mole of hydrogen to form dihydrostrepto-mycin B. The hydrogenation did not cause any loss in activity. The activity of dihydrostreptomycin B was not impaired by carbonyl reagents and it did not yield maltol on treatment mth alkali. 

Table 2 Physicochemical and GC Properties of Some Carbonyl Reagents and Their Analogs for Derivatization of Amino Compounds...

Tyrosine is converted to phenol by an enzyme, /3-tyrosinase, studied especially by Japanese workers (456, 654, 658, 879). The enzyme, which has been partially purified, is inhibited by carbonyl reagents and is dependent on pyridoxal phosphate. The reaction is mechanistically probably (593) very similar to the tryptophanase reaction and is discussed when considering the function of pyridoxal phosphate (p. 91). 

In this context, controlling the geometry of the formed enamine intermediate shows up as the first very important issue that has to be controlled if a highly stereoselective reaction is desired. Condensation of a secondary amine with an aldehyde or a ketone can lead to the formation of two diastereoisomers, Z or E, in varying proportions depending on the nature of the carbonyl reagent and the... 

The effect of inhibitors was investigated. Monoamine oxidases are inhibited by iproniazid but not by isoniazid. The plasma enzyme was inhibited by both reagents. Diamine oxidases are inhibited by cyanide, carbonyl reagents, and by isoniazid. The amine oxidase of plasma was inhibited by all three reagents. Therefore, although the substrate specificity of this enzyme tends to be more closely related to that of monoamine oxidase, its inhibition pattern resembles that of the diamine oxidases. 

Lithium aluminium hydride LiAlH is a useful and conveuient reagent for the selective reduction of the carbonyl group and of various other polar functional groups. It is obtained by treatment of finely powdered lithium hydride with an ethereal solution of anhydrous aluminium chloride ... 

The isopropyl group could be derived from a carbonyl group and a Grignard reagent in two ways ... 

Another feature of the Pd—C bonds is the excellent functional group tolerance. They are inert to many functional groups, except alkenes and alkynes and iodides and bromides attached to sp carbons, and not sensitive to H2O, ROH, and even RCO H. In this sense, they are very different from Grignard reagents, which react with carbonyl groups and are easily protonated. 

Analyze the following structures so as to determine all the practical combinations of Gng nard reagent and carbonyl compound that will give nse to each... 

The characteristic reactions of aldehydes and ketones involve nude ophihc addition to the carbonyl group and are summarized m Table 17 5 Reagents of the type HY react according to the general equation... 

Cyclic Peroxides. CycHc diperoxides (4) and triperoxides (5) are soHds and the low molecular weight compounds are shock-sensitive and explosive (151). The melting points of some characteristic compounds of this type are given in Table 5. They can be reduced to carbonyl compounds and alcohols with zinc and alkaH, zinc and acetic acid, aluminum amalgam, Grignard reagents, and warm acidified iodides (44,122). They are more difficult to analyze by titration with acidified iodides than the acycHc peroxides and have been sucessfuUy analyzed by gas chromatography (112). 

The highly ionic thaHic nitrate, which is soluble in alcohols, ethers, and carboxyhc acids, is also a very useful synthetic reagent. Oxidation of olefins, a,P-unsaturated carbonyl compounds, P-carbonyl sulfides, and a-nitrato ketones can aH be conveniently carried out in good yields (31,34—36). 

The reaction involves nucleophilic substitution of for OR and addition of R MgX to the carbonyl group. With 1,4-dimagnesium compounds, esters are converted to cyclopentanols (40). Lactones react with Grignard reagents and give diols as products. 

Alkyl-l,3-oxazolines are prepared to protect both the carbonyl and hydroxyl groups of an acid. They are stable to Grignard reagents and to lithium aluminum hydride (25°, 2 h). ... 

The carbonyl groups in the diketo- and keto-aleohol bases are not readily detected by the usual reagents and as these bases can be reduced to the dihydrie alcohols, it was assumed at first that lobeline and lobelanine contained one and two ether linkages respectively and formulse based on this assumption, and satisfying the other experimental evidence then available, were put forward by Wieland, Schopf and Hermsen, of which that for lobeline (II) may be quoted as an example. 

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