Narender Nama

Hypoiodous acid-catalyzed regioselective geminal addition of methanol to vinylarenes: synthesis of anti-Markovnikov methyl acetals

A novel metal-free, catalytic geminal dimethoxylation of vinylarenes based on in situ generated HOI species from iodide salt and oxone is reported. The preliminary mechanistic investigations suggest that the key factor for achieving the anti-Markovnikov regioselectivity is the semipinacol rearrangement of an iodo functionalized intermediate, which is confirmed by an isotope labeling experiment. In addition, the reaction involves the de-iodination of a co-iodo intermediate via its oxidation to hypervalent iodine species rather than a common iodide abstraction by electrophiles. The HRESI-MS studies support the conversion of monovalent iodine containing intermediates to trivalent iodine intermediates during the catalytic conversion of aromatic alkenes into the corresponding terminal acetals.

Metal-free, catalytic regioselective oxidative conversion of vinylarenes: a mild approach to phenylacetic acid derivatives

A new synthetic approach towards the synthesis of phenylacetic acids from aromatic alkenes has been developed for the first time under mild conditions by employing non-toxic reagents such as molecular iodine and oxone. This metal-free catalytic regioselective oxygenation of vinylarenes proceeds via tandem iodofunctionalization/de-iodination induced rearrangement.

ortho-Alkenylation of anilines with aromatic terminal alkynes over nanosized zeolite beta

A simple, efficient and environmentally benign catalytic system has been successfully developed for highly regioselective electrophilic alkenylation of anilines with aromatic terminal alkynes over nanosized zeolite beta, which exhibits the highest catalytic activity among other conventional zeolites. The scope of the reaction was explored with various anilines and alkynes. However, the substrates (aniline or alkynes) with strong electron-withdrawing groups failed to react under the present catalytic conditions (except 4-nitroaniline). Moreover, the catalyst is recyclable and can be reused without significant loss in its catalytic activity.

Chemo- and regioselective head-to-tail heterodimerization of vinylarenes with 1,1-diphenylethene over a heterogeneous catalyst (Snβ zeolite)

In the presence of Snβ zeolite, vinylarenes undergo the highly chemo- and regioselective head-to-tail heterodimerization with 1,1-diphenylethene to form the corresponding alkenes in good to excellent yields. The scope of the reaction was explored by various vinylarenes with 1,1-diphenylethene. However, the substrates with strong electron-withdrawing groups failed to react with 1,1-diphenylethene under the present catalytic conditions. Moreover, the Snβ zeolite is recyclable and can be reused without significant loss in its catalytic activity.

Synthesis of α,β-unsaturated ketones from alkynes and aldehydes over Hβ zeolite under solvent-free conditions

A facile Hβ zeolite-catalyzed strategy has been successfully developed for the synthesis of α,β-unsaturated ketones from alkynes and aldehydes under solvent-free conditions. The reaction proceeds via tandem hydration/condensation of alkynes with aldehydes to afford a range of α,β-unsaturated carbonyls in good to excellent yields.

An Aqueous Media-Controlled Stereospecific Oxidative Iodination of Alkynes: An Efficient Access to (E)-Diiodoalkene Derivatives

A new and versatile approach for the stereospecific iodination of alkynes using cheap, air stable and non-toxic reagents in aqueous media has been developed. This protocol is tolerant of various functional groups, and provides a broad range of vicinal diiodoalkenes with exceptional E-selectivity under mild conditions. Scale-up reactions (up to 5 g) established the proficiency of this protocol and highlight the feasibility of large scale reactions.

Hβ Catalyzed Condensation Reaction Between Aromatic Ketones and Anilines: To Access Ketimines (Imines)

A simple approach for the formation of imines by condensation of ketones and anilines over heterogeneous catalyst (Hβ zeolite) has been successfully developed. The present catalytic system scope was explored for various aromatic ketones and anilines. Furthermore, Hβ zeolite can be easily separable and recycled several times (five times) without considerable loss of its catalytic activity.Graphical Abstract