Indian Journal of Chemistry Vol. 55B, July 2016, pp. 833-853 Advances in Contemporary Research Advanced synthetic and pharmacological aspects of 1,3-oxazoles and benzoxazoles Ambreen Ghani*, Erum A Hussain, Zubi Sadiq & Narjis Naz Department of Chemistry, Lahore College for Women University, Lahore 54000, Pakistan E-mail: ambreen_atiq@yahoo.com; erum.hussain@gmail.com Received 9 December 2014; accepted (revised) 31 March 2016 Broad bio-spectrum of 1,3-oxazole and benzoxazole has created an attractive platform for synthetic chemists to introduce structural modification in its nucleus by straight forward access to new approaches. Owing to its fascinating features and interesting pharmacological activities, many researchers have proved that oxazole is an active agent in treating different diseases. Based on this fact, this article outlines intramolecular and two component intermolecular cyclization to oxazoles and benzoxazoles. The theme is well documented in this review article covering the era from 2007 till present. Moreover, bioactivity and mechanistic insights are provided with different synthetic approaches, encompassing various pathways. Keywords: Benzoxazole, bisoxazole, oxazole, synthesis, bioactivity Oxazole, a heterocyclic scaffold is believed to occur in various structurally complex biologically active natural products. Several oxazole possessing compounds have been isolated from plants and marine natural origins such as Martefragin A and Almazol D (Figure 1) isolated from Martensia fragiles 1 and red algae 2 respectively. These naturally occurring molecules demonstrate the versatile synthetic, medicinal and industrial applications of oxazoles. The diversified oxazole analogues with multi-directional potential stands out in modern organic chemistry and provides the sharp sword that combat future challenges related to medicinal and synthetic aspects. Considerable attention has been made in formulating high yield synthetic approaches from simpler chemical catalog. Generally, this widespread highly substituted building block is attained from intramolecular cyclocondensation reactions using dehydrating agents or by intermolecular cyclization through -substituted ketones as intermediates 3-10 . Nevertheless, direct eco-friendly metal catalyzed approaches have also been extensively used that overcome the limitations of multi-step processes 11-14 . The amazing pharmacological profile of oxazole includes antibiotic, anti-inflammatory, hyperglycemic, antiproliferative, antihistaminic, antiparasitics and anti-tuberculosis activities 15-17 . For instance, the use of drug containing oxazole is oxaprozin having non- steroidal anti-inflammatory activity. Owing to its privileged importance, a lot of work has been done on synthesis and medicinal features of oxazoles 18 . To the best of our knowledge, previous reviews 19 on oxazole focused on specific aspects of its synthesis were published during 2008 to 2014. We hereby wish to describe synthetic routes involving metal catalyzed, metal free, microwave assisted and different multicomponent domino approaches adopted for oxazoles. Metal catalyzed procedures have been studied by emphasizing their specificity, while their promising mechanistic insight has also been provided. Metal free transformations for oxazoles, contribute a great deal in organic synthesis. Microwave technology being highly preferred method of heating provides better possibilities in chemical synthesis. While MCR approach offer a clear direction with atom economy, ecofriendly simplified steps and effective use of resources for 1,3-oxazoles. In the preceding sections a brief description of numerous synthetic strategies and pharmacological implications of 1,3-oxazole hetrocycles is presented in order to provide an idea for future directions on this potential molecule. N H O O N N RO N H O N OOC NH Figure 1 — Oxazoles from natural sources