The formation and reactions of some new functionally substituted derivatives of (η 5-cyclopentadienyl dicarbonylnitrosylchromium (cynichrodene)

Abstract

The reaction between cynichrodenoic acid, (η 5-C 5H 4COOH)Cr(CO) 2NO ( 6) and phosphorus pentachloride produces cynichrodenoyl chloride ( II) in high yield. Subsequent reaction of 11 with sodium azide affords cynichrodenoyl azide ( 12), which undergoes Curtius rearrangement to form cynichrodenyl isocyanate ( 13). Subsequent hydrolysis of isocyanate 13 in aqueous KOH solution yields aminocyanichrodene ( 14). Azide 12 also undergoes Curtius rearrangement in the presence of benzyl alcohol to produce benzyl N-cynichrodenylcarbamate ( 15). Reactions of acid chloride 11 with ammonia, dimethylamine or aniline lead to the corresponding carboxamides ( 16–18). Amide 16 is readily dehydrated to produce cynichrodenecarbonitrile ( 19). Reactions of acid chloride 11 with either benzyl alcohol or hydroxymethylferrocene generate the corresponding esters ( 20–21), whereas treatment of a tetrahydrofuran solution of 11 with pyridine affords cynichrodenecarboxylic anhydride ( 22 in low yield. Reactions of acetylcynichrodene ( 2) with organolithium reagents, leading to both carbonyl addition and condensation products, have been investigated. Treatment of 2 with lithium diisopropylamide in diethyl ether solution produces the self-condensation product 1,3-dicynichrodenyl-but-2-en-1-one ( 24). Acetyl derivative 2 and benzaldehyde also undergo Claisen-Schmidt condensation in the presence of lithium diisopropylamide to afford cinnamoylcynichrodene ( 27).