Richa Prakash

[Hydroxy(tosyloxy)iodo]benzene Mediated α-Azidation of Ketones

Abstract: Reaction of various ketones with [hydroxy(tosyloxy)iodo]benzene (HTIB) followed by treatment of the α-tosyloxy ketones thus generated in situ with NaN 3 offers a one-pot procedure for the synthesis of α-azido ketones. The HTIB used in this conversion may also be generated in situ by using iodosobenzene in combination with p -toluene-sulphonic acid. Keywords: Hypervalent iodine, α-azido ketones, [hydroxy(tosyloxy)iodo]benzene, iodosobenzene. Introduction The application of organohypervalent iodine reagents is a fertile and attractive field in organic synthesis [1]. Of the various hypervalent iodine reagents, iodobenzene diacetate (IBD) [2] and [hydroxy(tosyloxy)iodo]benzene (HTIB) (Koser’s reagent) [3] have been found to be more versatile than other reagents such as iodosobenzene (IOB), etc. The relatively lesser utility of IOB is due to its polymeric nature [4], which makes it insoluble in common solvents. To overcome such difficulties, combination reagents were developed. For example, the utility of IOB is greatly enhanced when it is combined with acids [5], bases [6] or salts [7]. These reactions are thought to proceed via generation

α,α‐Dibromoketones: A Superior Alternative to α‐Bromoketones in Hantzsch Thiazole Synthesis

Abstract α,α‐Dibromoketones (2) have been found to be a superior alternative to the conventionally used α‐bromoketones (1) for performing the Hantzsch thiazole synthesis.1 These crystalline, nonlachrymatory compounds are more reactive than 1 as demonstrated by their reaction with 3,5‐dimethyl‐1‐thiocarboxamide (5).

Synthesis of 3β,3β,5‐tribromoacetyl‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one by Bromination of Dehydroacetic Acid

Abstract Bromination of dehydroacetic acid giving rise to 3β,3β,5‐tribromoacetyl‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one is described.

α,α-Dibromoacetophenones mediated synthesis of some new 7H-7-alkoxy-3-alkyl/phenyl-6-aryl-s-triazolo[3,4-b][1,3,4]thiadiazines and their antimicrobial evaluation

A series of new 7H-7-alkoxy-3-alkyl/phenyl-6-aryl-s-triazolo[3,4-b][1,3,4]thiadiazines (3, 4) were synthesized by the reaction of various α,α-dibromoacetophenones 1 with 3-alkyl/phenyl-4-amino-5-mercapto-s-triazoles (2) in different alcoholic solvents in good yields. All the newly synthesized compounds (3, 4) were screened for their in vitro antibacterial and antifungal activity. Biological activities of these compounds were compared with those of the commercially available antibiotic, ciprofloxacin and antifungal agent, amphotericin-B. The title compounds showed good activity against the Gram-positive bacteria, Staphylococcus aureus and Bacillus subtilis and the yeasts, Saccharomyces cerevisiae and Candida albicans.