Azodicarboxylic acid reductions with

Reductions with azodicarboxylic acid, a diimide precursor s. 77,83 preferential reduction of ar. 0x0 compounds s. E. E. van Tamelen, M. Davis, and M. F. Deem, Ghem. Comm. 1965, 71... 

Tosylhydrazine Reduction with tosylhydrazine and azodicarboxylic acid... 

Reductions with azodicarboxylic acid, a diimide precursor... 

In order to transform the spirocyclic enone 445 to ( )-elwesine (439) and ( )-epielwesine (449), it was treated with boron trifluoride and dimethylsulfide to cleave the Al-carbobenzyloxy protecting group, and cyclization of the resulting amino enone spontaneously ensued to produce ( )-dihydrooxocrinine (447). Reduction of carbonyl function of 447 with sodium borohydride afforded ( )-3-epielwesine (449), which was converted to ( )-elwesine (439) by inversion of the hydroxyl function at C-3 via a Mitsunobu protocol using diethyl azodicarboxylate, triphenylphosphine, and formic acid. Attempted reduction of 447 directly to 439 by a Meerwein-Ponndorf-Verley reduction or with bulky hydride reagents gave only mixtures of 449 and 439 that were difficult to separate. 

It seemed prudent that the same ethers be examined in the absence of potentially labile functionality, thus removal of unsaturation in 262 and 263 was considered. Hydrogenation of 259 over Pd/C or Pt was unsuccessful in either case reduction of the peroxide group was problematical. Hydrogenation over Wilkinson s catalyst gave a new product, but with the unsaturation retained. While selective alkene hydrogenation can sometimes be achieved in the presence of a peroxide bond, the double bond of 259 was apparently too hindered in this case. Diimide, on the other hand, worked reasonably well for this reduction. Thus, treatment of 259 in dichlo-romethane solution with potassium azodicarboxylate followed by addition of acetic acid led, after several days, to roughly 60% conversion of 259 to the saturated version, 264. Now, ether formation as before provided the saturated methyl and benzyl ethers 265 and 266, respectively, in good yields. 

The synthetic potential of a simple method for the direct introduction of nitrogen into the 5-position of the pyrimidine ring is illustrated by the synthesis of 1,3-dimethyluric acid (15) from 1,3-dimethyluracil-6-amine by reaction with diethyl azodicarboxylate, reduction to 5-[(ethoxycarbonyl)amino]-l,3-dimethyluracil-6-amine, and thermal ring closure. "... 

P-Lactams.1 A biomimetic synthesis of /3-lactams from chiral amino acids such as L-serine has been developed by Mattingly and co-workers. The protected amino acid (1) is first converted into the O-alkyl or O-acyl hydroxamate (2), which undergoes cyclization to derivatives of l-hydroxy-2-azetidinones on treatment with triphenylphosphine-carbon tetrachloride. This cyclization is also possible with triphenylphosphine-diethyl azodicarboxylate.2 The final step involves reduction of the N—OH group with TiClj.3 The advantage of this method over that of Wasserman (9,428), which involves cyclization of /3-haloamides, is that a strong base such as NaH is not required. 

Kauhaluoma and Samanta used miinchnone as the key intermediate to obtain a triazole core (Scheme 9.41). Starting with Ameba resin 351, 3.84 equiv of amino acid ester 352 and 25 equiv of NaBHaCN were employed for the reductive alkylation in 1% acetic acid in DMF at room temperature for 12 h. Resin 353 was treated with 10 equiv of carboxylic acid chloride 354 in the presence of 12 equiv of A,A-diisopropylethylamine in DCM at room temperature for 12h to form amide 355, which was treated with 5% KOH in dioxane H20 (3 1) for 4h to give the corresponding carboxylic acid. Resin 356 was treated with 23.5 equiv of acetic acid anhydride, 3 equiv of DEAD (diethyl azodicarboxylate) 357, and 3 equiv of 4-phenyl-4/f-l,2,4-triazoline-3,5-dione 358 in DCM at room temperature for 5-10 h, giving the miinchnone intermediate 359, which reacted with compound 357 or 358 to form resin 360. Treatment of this with 30% TFA in DCM at room temperature for 1.5 h resulted in cleavage from the resin, producing 361. 

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