Reactions of Diferrocenylmorpholino- and -Methylsulfanyl-cyclopropenylium Salts with β-Dicarbonyl Compounds and Diethyl Malonate

Abstract

2,3-Diferrocenyl-1-morpholinocyclopropenylium tetrafluoroborate reacts with ethyl acetoacetate, ethyl benzoylacetate, and diethyl malonate in the presence of triethylamine to yield 3-[acyl(ethoxycarbonyl)]-, 3-(diethoxycarbonyl)-methyl-3-morpholino-1,2-diferrocenylcyclopropenes (3a–c), and 3-[acyl(ethoxycarbonyl)]- and (diethoxycarbonyl)-methylidene-1,2-diferrocenylcyclopropenes (4a–c) in a ca. 1:1.5 ratio. 2,3-Diferrocenyl-1-methylsulfanylcyclopropenylium iodide with the same substrates affords compounds 4a,b (∼10–15%), 3-[acyl(ethoxycarbonyl)]methyl-3-methylsulfanyl-1,2-diferrocenylcyclopropenes (5a,b) (∼8–10%), 2-acyl-3,4-diferrocenyl-5-methylsulfanylcyclopentadienones (6a,b), ethyl 2-acyl-3,4-diferrocenyl-5-methylsulfanylpenta-2,4-dienoates (7a,b; 8a,b), and ethyl 3,4-diferrocenyl-2-methylsulfanyl-6-oxohexa(hepta)-2,4-dienoates (9a,b). The spatial structure of ethyl Z,E-3,4-diferrocenyl-2-methylsulfanyl-6-oxohepta-2,4-dienoate (9b) was established based on the data from x-ray diffraction analysis. Electrochemical properties of 3-[acyl(ethoxycarbonyl)]- and (diethoxycarbonyl)-methylidene-1,2-diferrocenylcyclopropenes (4a–c) are studied.

Keywords:

• 3-[Acyl(ethoxycarbonyl)]methyl-3-methylsulfanyl-1,2-diferrocenylcyclopropenes
• 3-[acyl(ethoxycarbonyl)]methyl-3-morpholino-1,2-diferrocenylcyclopropenes
• diferrocenyl(methylsulfanyl)cyclopropenylium
• diferrocenyl(morpholino)cyclopropenylium
• electrochemistry
• ethoxycarbonyl group migration
• ethyl 2-acyl-3,4-diferrocenyl-5-methylsulfanylpenta-2,4-dienoates

ACKNOWLEDGMENTS

This work was supported by the DGAPA-UNAM (Mexico, Grant IN 214209). Thanks are due to Eduardo Arturo Vàzquez Lopez and Juan Manuel Martìnez Mendoza for their technical assistance.

Notes

Note. E⁰ = (E _pa + E _pc)/2 reported vs ferrocene in 0.1 M TBABF₄–acetonitrile. Scan rate 0.10 Vs⁻¹.