Aldehydes hydroxamic acid synthesis

Recently, Porcheddu and Giacomelli have reported a convenient one-step procednre for the synthesis of hydroxamic acids 215 starting from aldehydes 213 and solid-snpported A-hydroxybenzenesulfonamide 214 (Scheme 92). The hydroxamates are isolated in good to high yields and purities by simple evaporation of the volatile solvents, after treatment of the crude reaction mixture with sequestering agents (216 and 217). 

Synthesis of hydroxamic acids from aldehydes and N-sulfonylhydroxylamine also used as a color test for aldehydes (see 1st edition). 

Angelo Angeli s name, along with that of Enrico Rimini (1874—1917), is often associated with the chemical reaction that bears their names. In 1896 Angeli, and independently Rimini, discovered the reaction between an aldehyde and a sulfonamide to form a hydroxamic acid they published their discoveries in the same year [115, 116]. The reaction was mainly used as a chemical test in the dairy industry for detecting the presence of aldehydes as a consequence of food storage. The Angeli-Rimini reaction has been recently applied in solid-phase synthesis [117]. 

Scheme 42 Synthesis of aldehydes and ketones from resin-boimd hydroxamic acids...

The majority of reported solid-phase combinatorial syntheses of the lactam core utilize a [2-i-2] cycloaddition reaction of ketenes with resin-bound imines [33-41]. A further development of the Staudinger reaction was reported by Mata and coworkers using Mukaiyama s reagent [42]. In addition, a stereoselective synthesis of chi-rally pure P-lactams has been performed as a first utilization of polymer-supported oxazolidine aldehydes [43]. Other strategies include an ester enolate-imine condensation [44], an Hg(OCOCF3)2-mediated intramolecular cydization [45], and Miller hydroxamate synthesis [46]. Because of the variability derived from the scaffold synthesis, not many attempts have been made to derivatize the resin-bound lactam template [47]. One of the most detailed descriptions of a versatile (3-lactam synthesis on a resin employed amino acids tethered as esters on Sasrin resin [48]. 

Salvino et aL showed the synthesis of a simple linker to generate aldehydes and ketones from the corresponding acids via immobilization as hydroxamate resin. The starting resins 276 were obtained by synthesis of hydroxy-lamines on soHd support (from Wang resin. Scheme 42) that were coupled to carboxyhc acids and N-protected amino acids 277. Depending on the substi-... 

Amidation. A number of other various amidation reactions have been conducted using BOP. Such preparations include A) O-dimethyl hydroxamates of amino acids and peptides (precursors of chiral peptidyl aldehydes), heterocyclic amide fragments in the synthesis of macrolide and porphyrin models, dan-sylglycine anhydride as a mixed sulfonic-carboxylic imide by dehydration-cyclization of dansylglycine, and selective monoacylation of heterocyclic diamine in carbohydrate series (eq 9). ... 

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