The TBS group was later recovered with tetra- normal-butylammonium fluoride TBAF in THF to give alcohol 28 in 91 yields.
The second portion of the synthesis is presented in schemes 10.
Protection of the commercially available hydro ester 22 with tertiary-butyldimethylsilyl chloride TBDMS-Cl gave silyl ester 23.
The ester 23 on reduction with Li BH4 gave the alcohol.
Synthesis of Benzohydroxamic Acid 3 The synthesis of compound 3 was achieved by reacting methyl benzoate 1 and hydroxylamine 2. Synthesis of Hydroxamates Using N, N1, NII–trimethoxy-N, NI, NII-trimethyl Phosphorus Triamides 5 Nui et al 31 reported the conversion of aromatic and aliphatic carboxylic acids, including sterically hindered substrates directly to hydroxamates using N, NI, NII-trimethoxy-N, NI, NII–trimethyl phosphorus triamide 5.
29 The wide biological application of hydroxamates necessitates the review of its synthesis and biological applications. General Synthesis of Weinreb Amides Hydroxamic acids are prepared usually from esters or acid chlorides or carboxylic acids.2.1. Further, T3P has also been employed to activate the hydroxamtes leading to isocyanates via Lossen rearrangement 34. NHC–catalyzed Synthesis of Hydroxamic Acids N-Heterocyclic carbene NHC catalyzed amidation of a variety of aryl, alkyl, alkenyl and heterocyclic aldehydes with nitroso compounds is a powerful method for the synthesis of N-aryl hydroxamic acids in excellent yields. Chemoselective Esterificaiton Using Imidazole Carbamates Imidazole carbamates and ureas are used as chemoselective esterification and amidation reagents. A simple synthetic procedure allows the conversion of a wide variety of carboxylic acid to hydroxamates. Synthesis of Weinreb Amides Using Triazime Intermediates De Luca et al 37 reported the successful large scale synthesis of weinreb amide through a convenient and simple one-flask method via 2-chloro-4,6-dimethoxy-1,3,5-triazine intermediate 20. 17, 18 These class of compounds are used in the design of therapeutics targeting cancer 19, 20 e.g. histone deacetylases HDACs inhibitors like vorinostat, belinostat, panobinostat and trichostatin A, 21 cardiovascular diseases 22 e.g. hydroxyurea, 24 Alzheimer s, 25 malaria 26, 27 e.g.