Facile Reduction Of Acylferrocenes Using Sodium Borohydride In Presense Of AlCl₃(or ZnCl₂)

The reduction of carbonyl group in acylferrocene to a methylene is a extremely useful and widely reported synthetic pathway to synthesize alkylferrocene. Alkylferrocenes thus obtained are ont only important intermediates for synthesizing ferrocenyl compounds but also burning catalyst of some fuels and burning rate catalyst of soild rocket propellant. It has extremely important applicable value to seek an inexpensive, safe to handle, easy to manipulate and environmental friendly agent for reducing acylferrocene to the corresponding alkylferrocene. Herein, we report an efficient method for synthesis alkylferrocenes by reduction of corresponding acylferrocene using NaBH₄/AlCl₃ and NaBH₄/ZnCl₂ in THF. This paper contains three aspects as following.1. The Orthogonal Experiment Design Method(OEDM) is applied to investigate the reduction factors, which include amount of sodium borohydride and aluminun chloride, reaction temperature and virious solvents. The best reaction molar ratio is FcCOCH₃:NaBH₄:AlCl₃=1:4:1.5 and the reaction temperature is 50-60℃2. The OEDM is applied to investigate the reduction factors, which include amount of sodium borohydride and znic chloride, reaction temperature. The best reaction molar ratio is FcCOCH₃:NaBH₄:ZnCl₃=1:2.5:2 and the reaction temperature is 40-60℃3. Eleven ferrocenyl aldehyde and ketone derivatives were synthesized and effectively reduced to alkylferrocene by method 1 and 2 above. The experimetal results show that the two methods are easying to operate with high yields and lower price.