Highly enantioselective synthesis of chiral chromenes and tetrahydroquinolines is achieved by combining asymmetric copper-catalyzed allylic substitution with Grignard reagents and an efficient intramolecular Heck reaction. Moreover, the exocyclic double bond formed in the cyclisation was subjected to RCM, hydroboration and hydrogenation illuminating the synthetic versatility of these heterocycles.

A highly enantioselective (S)-diphenylpyrrolinol triethylsilyl ether promoted tandem oxa-Michael-aldol reaction of alpha,beta-unsaturated aldehydes with salicylaldehydes has been developed; the method affords one-pot access to chiral and synthetically useful chromenes in high yields and high enantioselectivities from readily available compounds.

An efficient diastereo- and enantioselective Friedel-Crafts alkylation of indoles with 3-nitro-2H-chromenes catalyzed by diphenylamine-linked bis(oxazoline) and bis(thiazoline) Zn(II) complexes has been developed. This asymmetric Friedel-Crafts alkylation led to medicinally privileged indolyl(nitro)chromans in good yields with high enantioselectivities (up to 95% ee) and diastereoselectivities ...

A palladium-catalyzed reaction of 2-alkynylhalobenzenes with 2-alkynylphenols in the presence of PCy(3) is discovered, which provides an efficient and facile route to indeno[1,2-c]chromenes. This reaction works efficiently, leading to the corresponding products in good to excellent yields.

In the present work, bakers yeast catalyzed efficient synthesis of 2-amino-2-chromenes in methanol is presented. Here ultrasonication has dual role i.e. as a source energy for reaction and tool disruption cells. The cyclocondensation been essentially carried under neutral conditions, thus reducing possibility unwanted side reactions.

2H-Chromene is an important structural motif that exists in natural products and non-natural compounds possessing interesting biological activities. In this investigation, a highly efficient approach toward 2H-chromenes has been developed based on palladium-catalyzed coupling of N-tosylhydrazones and β-bromostyrenes. The mechanism of this reaction is proposed that involves the formation of viny...

Bismuth triflate (Bi(OTf)3) is identified as an efficient catalyst for the direct addition of isocyanides to 2H-chromene acetals. The large scope of isocyanides and chromene acetals makes them suitable substrates in this catalytic system. By this synthetic strategy, a polyfunctional molecular scaffold, 2-carboxamide-2H-chromenes could be prepared efficiently in one step up to 95% yield. In addi...

An efficient approach for the synthesis of functionalized 4-substituted-2-amino-3-cyano-4H-chromenes moderate to high yields (up to 98%) has been achieved via a tandem K2CO3 catalyzed conjugate addition-cyclization reaction of malononitrile and a range of Knoevenagel adducts previously formed from oxindole, pyrazolone, nitromethane, N,N-dimethylbarbituric acid or indanedione. This methodology d...

2H-Chromenes (2H-1-benzopyran derivatives) display a broad spectrum of biological activities. The 2H-chromene substructure is an important structural motif present in a variety of medicines, natural products, and materials showing unique photophysical properties. Hence, the structural importance of the benzopyran moiety has elicited a great deal of interest in the field of organic synthesis and...