A post-Passerini condensation transformation can be employed in the synthesis of three types of amides: α-hydroxy, α-oxy, and α-oxo amides. K2CO3 efficiently promotes the solvolysis of α-acetoxy amides to form α-hydroxy amides in methanol. 2-Acetoxy-2-(2-alkynyl­quinolin-3-yl)acetamides in basic methanol are cyclized to 1,3-dihydrofuro[3,4-b]quinoline-1-carboxamides via deacetylation and 5-exo-dig cyclization. Treatment of 2-hydroxy-2-[2-(phenylethynyl)quinolin-3-yl]acetamides with I2 in basic media produces pyrrolo[2,3-b]quinoline-2,3-diones. This cyclization involves intramolecular cyclization, dealkynylative aromatization, and oxidation of the secondary alcohol.

A base-mediated intramolecular hydroalkoxylation that was used to prepare a series of seven-membered S,O-heterocycles is described. 2-Thiopropargyl-3-hydroxymethyl quinolines were prepared starting from 2-mercaptoquinoline-3-carbaldehydes, via S-propargylation and reduction of a formyl group. Interestingly, 2-mercaptopropargyl-3-hydroxymethyl quinolines were converted into the corresponding oxathiepinoquinolines in the presence of t-BuOK. It is proposed that the S-propargyl moiety, in the presence of base, is converted into its allenyl isomer; subsequent addition of a hydroxyl group to the terminal double bond yields the 3-methyl-5H-[1,4]oxathiepino[5,6-b]quinoline in good to high yield. Notably, the procedure is adaptable to the conversion of N-propargyl indole-2-methanol into the corresponding intramolecular hydroalkoxylation product.