Rapid access to benzo-annelated heterocycles, naphthalenes, and polysubstituted benzenes through a novel benzannulation reaction

One‐Pot Synthesis of Biaryl Lactones by Sonogashira Cross‐Coupling Reactions of 4‐Chloro‐3‐formylcoumarin and Subsequent Domino [5+1] Cyclization/Deacetylation Reactions with 1,3‐Dicarbonyl Compounds

“…Herein, we report a new one‐pot synthesis of biaryl lactones by Sonogashira reactions of 4‐chloro‐2‐oxo‐2 H ‐chromene‐3‐carbaldehyde and subsequent cyclocondensation with 1,3‐dicarbonyl compounds. The cyclization step proceeds by a domino [5+1] cyclization/deacetylation process which has, to the best of our knowledge, not been reported so far 11. The substitution pattern of the products reported herein is not readily accessible by other methods.…”

Brønsted Acid‐Promoted Benzannulation of o‐Alkynylbenzaldehyde and Alkyne, and the Positive Effect of Propargyl Alcohol

“…Isochromenylium (benzopyrilium) ions I are often the key intermediate and generated in situ. [7] In addition to o-alkynylbenzaldehydes, its acetals and o-alkynyl-benzylalcohol/-acetophenone derivatives could also be the precursors to isochromenylium, and many metal complexes, including Au, [8] Ag, [9] Cu, [10] Pt, [11] Pd, [12] Zn, [13] Hg [14] and Re [15] have been applied with good efficiency and regioselectivity. Inexpensive, environmentally benign non-metal oxidants, [16] Brønsted acids [17] and Lewis acids [18] have also been developed for this purpose.…”

Synthesis of substituted-3-iodo-1H-pyrazole derivatives and their further modification under Sonogashira cross coupling reaction conditions

“…[12][13][14][15] Previous studies of intramolecular cyclisation or cycloisomerisation of 2-formylhetarylacetylenes has showed that the structure of products can vary depending on the nature of used materials. 12,16 For further studies of cyclisation reactions 1-(1-ethoxyethyl)-3-(phenylethynyl)-1H-pyrazole-4-carbaldehyde and 1-(1-ethoxyethyl)-3-nitro-4-(phenylethynyl)-1H-pyrazole were synthesized. Herewith the Sonogashira cross-coupling reaction of 1-(1-protected)-3-iodo-1H-pyrazole derivatives with phenylacethylene was investigated and applied for the synthesis of N-unprotected pyrazoles.…”