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We report here our synthetic approach to acetylenic esters of six different steroids. The use of flash vacuum pyrolysis (FVP) is a very appealing tool for the acetylenic moiety to efficiently cyclize and rearrange which allows access to medicinally and pharmaceutically valuable products. Each substrate was subjected to FVP. The products were analyzed, identified and characterized. Acetylenic esters of aromatic steroids resulted in 2 H -cyclohepta[ b ]furan-2-one, and 2 H -chromen-2-one derivatives, while aliphatic esters afforded unsaturated polycyclic hydrocarbons via elimination of propiolic acid. [Display omitted] • Acetylenic aromatic steroid esters react via carbene insertion reactions. • FVP of steroid esters provides direct access to prepare interesting fused steroid derivatives. • Acetylenic aliphatic steroid esters undergo elimination reaction via six-membered transition state. [ABSTRACT FROM AUTHOR]

Synthesis and flash vacuum pyrolysis (FVP) of acetylenic esters and ethers of paracetamol and aspirin and their analogues were performed. The products were analyzed, identified, and characterized. Acetylenic esters and ethers of paracetamol resulted in benzofuran, and cyclohepta[ b ]pyrrol-2(1 H)-one. Aspirin and its derivatives produced chromenones, xanthones, indenones, chromenes, and other heterocyclic compounds. [Display omitted] • Synthesis and FVP of aspirinderivatives. • Synthesis and FVP of paracetamol derivatives and analogues. • Valuable routes for synthesis of xanthones and chromenones by FVP. [ABSTRACT FROM AUTHOR]

1-aryl-1,2,3-triazole-4-carboxylate esters 1 - 13 , − 4-carboxamides 14–16 , ethyl 1-aryl-5-methyl/phenyl-1,2,3-triazole carboxylates 17–21 , − 4-carboxamides 22–24 , and 1,4,5-triphenyltriazole 25 have been synthesized via click reactions. Flash vacuum pyrolysis (FVP) for each triazole has been investigated. FVP of triazole-4-carboxylates gave mainly 4-hydroxyquinolin-2(1 H)-one and indole derivatives, while FVP of triazole-4-carboxamides gave indole and urea derivatives. In addition, unanticipated novel products were also isolated. All products were identified, analyzed, and fully characterized. • FVP reaction for twenty-five triazole derivatives were performed. • Indoles and quinolones are the major products from FVP of triazoles at 500–650 ºC. • Methyl triazole-4-carboxylates generate two quinolones isomers. • FVP of 5-substituted triazoles provides two positional isomers of indoles. [ABSTRACT FROM AUTHOR]

Flash vacuum pyrolysis (FVP) of aryl propargyl ether 9 produces 2-methylbenzofuran 21 , 2 H -chromene indanone 22 and benzocyclobutene 23. o -chloro- and bromo-aryl propargyl ethers 10 & 11 resulted mainly in methylbenzofurans 25 , 26 & 29 and 2 H -chromene derivative 27. On the other hand, FVP of arylpropargyl ethers with an active substituent at the ortho position of the aryl group 12 - 15 & 20 has resulted in interesting, unexpected products. All products were analyzed, fully characterized, and identified. Mechanisms are proposed for most of these FVP reactions. [Display omitted] • FVP reaction for twelve aryl propargyl ethers were performed. • Reaction products were analyzed, characterized, and identified. • Non-ortho substituted aryl ethers chose Claisen-rearrangement leading to 2-indanones and benzocyclobutene. • An active function group at the ortho position interacts with carbene intermediates to form interesting unexpected products. [ABSTRACT FROM AUTHOR]