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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]

• FVP of aminobenzo- and naphthofurans give formylbenzo- and naphthonitriles. • Absence of amino group renders cleavage of furan ring more difficult. • Substituted phenoxy and naphthoxy carbenes isomerize to benzaldehyde and naphthocarboaldehyde derivatives. Benzo- and naphthofuran carboxylates 1, 2 and carboxamides 3 , 4 were synthesized and pyrolysed by flash vacuum pyrolysis at 550 and 650 °C/10−2 mmHg. 2-Formylbenzonitrile 7 from benzofurans and 2-formylnaphthonitrile 14 from naphthofurans were isolated and identified as major products. The mechanism suggested for these pyrolytic reactions involves elimination of alcohol and amine from carboxylates 1, 2 and carboxamides 3 , 4 respectively, followed by extrusion of CO to form phenoxy and naphthoxycarbenes that leads to 7 and 14 respectively. [ABSTRACT FROM AUTHOR]