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An effective synthetic approach has been demonstrated for the construction of diverse bicyclic fused cyclopentenones from Morita–Baylis–Hillman (MBH) carbonates of propiolaldehydes. The present transformation was initiated through the propargylation of an alkenylamine with an MBH carbonate followed by the Pauson–Khand reaction of the product methyl 3-(alkenylamino)-2-methylenealk-4-ynoate. This facile method provides diverse scaffolds of cyclopentenone fused with aza-cycles having additional functionality in good yields.

An efficient approach for the highly diastereoselective construction of functionalized cyclopenta[d][1,2]oxazines via sequential oxyamination and Pauson-Khand reaction of readily accessible propargylic alcohols has been developed. Furthermore, the ring closing metathesis of these N-O linked 1,7-enynes afforded vinylated-[1,2]oxazines in good yields. The reduction of the N-O bond of the obtained cyclopenta[d][1,2]oxazine is accomplished to access cyclopentenone-based amino alcohols.

A convergent synthesis of the southern furan segment of novel furanocembranoids from Croton oblongifolius has been accomplished involving silver-catalyzed cyclization of alkynyl diol as the key ste...

A novel alkyne-assisted annulation reaction of MBH-carbonates of propiolaldehydes with α-nitro/bromo ketones is reported, providing a facile synthesis of substituted 2H-pyrans in good yields. This reaction divulges the inimitable reactivity of the MBH-carbonates of propiolaldehydes as C3-synthons wherein the alkyne functionality promoted the reaction without participating in the oxa-[3+3] annulation. The obtained products, having alkyne and ester functionalities, allowed further annulations to generate diverse pyrano[3,4-c]pyran-1-ones.

A convergent synthesis of the southern furan segment of novel furanocembranoids from Croton oblongifolius has been accomplished involving silver-catalyzed cyclization of alkynyl diol as the key step towards 2, 5-disubstituted furan ring formation.

Longanlactone analogues were synthesized using a route featuring Friedel-Crafts acylation, Sonogashira coupling and 1,3-dipolar cycloaddition reactions. Structure-activity relationships were investigated for neurotrophic activity. Compound 6 was found to have the most potent neurotrophic activity among all the synthesized analogues in Neuro2a cells as evidenced by a battery of in vitro/cell based assays for assessment of neurogenic and potential neurotrophic activity including neurite outgrowth assay and real time PCR for popular markers of augmented neurotrophic activity. Compound 6 might serve as a template for further development of highly effective neurotrophic molecules. (C) 2018 Elsevier Ltd. All rights reserved.

A novel metal-free approach to construct the tetrasubstituted furans from Morita-Baylis-Hillman (MBH)-carbonates of acetylenic aldehydes has been developed. This strategy involves the cascade nucleophilic substitution/5-exo-dig-cycloisomerization of MBH-carbonates with 1,3-dicarbonyl compounds to give uniquely substituted 2-furan-3-yl acrylates. Additionally, the obtained furan adducts open a new entry to naphthofurans through palladium-catalyzed decarboxylative benzannulation.

A novel metal-free approach to construct the tetrasubstituted furans from Morita–Baylis–Hillman (MBH)-carbonates of acetylenic aldehydes has been developed. This strategy involves the cascade nucleophilic substitution/5-exo-dig-cycloisomerization of MBH-carbonates with 1,3-dicarbonyl compounds to give uniquely substituted 2-furan-3-yl acrylates. Additionally, the obtained furan adducts open a new entry to naphthofurans through palladium-catalyzed decarboxylative benzannulation.