Bromination pyruvic acid

Acetoxy-17a-hydroxy-5a-pregnane-3,l 1,20-trione (40) is brominated in acetic acid under equilibrating conditions to give a solution of the 2a,4a-di-bromo compound (41). This is reduced by chromous chloride without further treatment, to the 4a-bromo compound (42). The recrystallized bromo compound (42) is then dehydrobrominated via the semicarbazone (43) which is converted without isolation into cortisone acetate (44) by treatment with pyruvic acid ... 

The synthesis of 23 was known to be amazingly simple pyruvic acid 22 is mixed with ammonia The yield is low, but who minds If you must have a low-yielding step, it is a good idea to have it at the start of the synthesis to avoid the waste of materials and energy. In this case, so much is achieved that a low yield is acceptable. Esterification gave the diester 21 R = Me which could be brominated with NBS (chapter 24) and combined with Ph P to give the phosphonium salt. This is the first branch complete. 

Succinic acid Bimsstein Pumice Blei Lead Bor Boron Borsaure Boric acid Borsaureanhydrid Boron trioxide Brenzcatechin Pyrocatechol Brenztraubensaure Pyruvic acid Brom Bromine Brom-Bromo-Bromcyan... 

The subsequent stages from pregnan-3a-ol-ll,20-dione acetate (I) to cortisone have been recorded by Kritchevsky et al. (1952) (Fig. 4). The enol acetate (II) of I upon treatment with perbenzoic acid forms the epoxide (III), which without isolation is hydrolyzed directly to pregnane-3a,17 -diol-ll,20-dione (IV). Bromination at C-21 (V) and mild treatment with alkali produces the 21-hydroxy derivative (VI), which is oxidized with N-bromoacetamide to dihydrocortisone (VII). Bromination (at C-4) of the 21-acetate of VII followed by dehydrobromination with semi-carbazide leads to the semicarbazone of cortisone acetate (VIII), which can be cleaved in a facile manner with pyruvic acid to cortisone acetate. Under suitable conditions, it is possible to accomplish the oxidation at C-3 and bromination of the ketone at C-4 in one step by means of N-bromoacetamide (Hershberg, Gerold, and Oliveto, 1952b). This synthesis of cortisone acetate from desoxycholic acid outlined in Figs. 3 and 4 is one of the most efficient bile acid processes, since it does not suffer from the difficulties outlined under Section II.2. 

Benzene ring system Peroxybenzoic acid Succinic acid Pumice Lead Boron Boric acid Boron trioxide Pyruvic acid Bromine Bromo-... 

Pyruvic acid (an -keto-add). (a) Pyruvic acid decolotirizes bromine water and potassium permanganate solution. It reduces ammoniacal silver nitrate. 

The sialic acid aldolase-catalyzed condensation of D-mannose 8 and pyruvate led, in an excellent yield, to the synthesis of KDN 9 [33], a natural deaminated neuraminic acid first isolated from rainbow trout eggs [34] and then discovered in other species. The discovery that sialic acid aldolase accepts as substrates D-mannose substituted on the 2-position, even by bulky substituents such as phenyl, azido, or bromine, opened the route to novel unnatural sialic acid derivatives [35-39]. Pentoses also are substrates. N-Substituted neuraminic acids could be prepared either directly from the corresponding Af-substituted mannosamine, such as N-thioacyl derivatives [40], or after reduction and acylation of 5-azido-KDN [41]. Recently, AT-carbobenzyloxy-D-mannosamine was converted, in a good yield, into the N-carbobenzyloxy-neurarninic acid, further used as a precursor of a derivative of castanospermine [42]. 

Method III) Oxazoles with ester-linked phosphonic acids 38 that were prepared from pyruvate esters 37, which were obtained via Fischer esterification as previously reported, were brominated using copper (II) bromide and subsequently cyclised with urea followed by TMSBr-mediated deprotection of phosphonate diester gave oxazoles 38 [77],... 

The above structure is confirmed by the results obtained by periodic acid oxidation 93), Sucrose consumes three moles of periodic acid, and one mole of formic acid is formed. (See earlier discussion in this chapter.) After bromine oxidation of the tetraaldehyde and subsequent hydrolysis, hydroxy-pyruvic, D-glyceric, and glyoxylic acids are obtained. (For a discussion of this method see p. 215.)... 

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