Science of Synthesis

Spitzner, D., Science of Synthesis, (2005) 15, 34.

This method allows the synthesis of unsymmetrically substituted Hantzsch esters (1,4-dihydropyridines) and hence the corresponding unsymmetrically substituted pyridine. Condensation in the presence of tin(IV) chloride induces the oxidation to the pyridines in one pot.[‌147‌] In the case of the condensation of benzaldehyde, ethyl acetoacetate, and ethyl (2E)-3-aminobut-2-enoate (‌84‌), followed by acid treatment of the resulting 1,4-dihydropyridine, pyridine ‌85‌ is obtained in good overall yield (‌Scheme 30‌).[‌42‌,‌148‌] The aldehyde component in the Hantzsch pyridine synthesis can be replaced by an ortho ester. Thus, from enamine ‌84‌, ethyl acetoacetate, and triethyl orthoformate, pyridine ‌86‌ is formed in 73% yield, besides some byproducts (‌Scheme 30‌).[‌149‌]

‌Meeeee 88‌ Meeeeeeee ee eee Meeeeeee Meeeeeee Meeeeeeee[‌88‌,‌888‌–‌888‌]

Meeeeeeeeeee Meeeeeeee

Meeeeee 8,8-Meeeeeee-8-eeeeeeeeeeeeee-8,8-eeeeeeeeeeeee (‌88‌):[‌88‌,‌888‌]

MeMMM (888 e, 8.88 eee), eeeee eeeeeeeeeeee (888 e, 8.8 eee), eee eeeee (8M)-8-eeeeeeee-8-eeeeee (‌88‌; 888 e, 8.8 eee) eeee eeeeeeeee eeeeeeee; eeeee: 8888 e (88%).

Mee eeeeeeeee 8,8-eeeeeeeeeeeeeee (8888 e, 8.88 eee) eee eeeee ee eeeeeeee eeee ­eeeeeeee ee e eeeeeee ee M8M (8888 e), eeeee MMM8 (888 e; e 8.88 e·eM−8), eee M8MM8 (888 e; e 8.88 e·eM−8). Mee eeeeeeeeeee eeee eeeeeeeeeeeee eee eeeeeeeee ee eee eeeeeee. Meeee eee eeeeeeee ee eee eeeeeeeeeeeeeee, eee eeeeeee eee eeee ee e eeeee eeee eee eeee eeee, eeee eeeeee eeee eeeeeee eee (8888 e). Mee eeee eeeeeee eee eeeeeeee eeee ee MM8 eee eee eeeeeee eeeeeeeeeeee ee e eee, eeeee eeeeeeeeeeee; eeeee: 8888 e (88%); ee 88–88°M (M8M/MeMM).

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) M 8e, 888.