Reduction of a Carbonyl Compound Using Baker's Yeast An Undergraduate Laboratory Synthesis of Ferrocenylmethanol Richard E. Bozak, Michael E. Prater, and Ronald J. Hicks California State University, Hayward, Hayward, CA 94542
The transformation of ferrocenecarboxaldehyde to the corresponding alcohol using the intact cells of actively fermentine baker's veast is a simple, inexpensive experiment demonstrating the general features of microbial redudion. The entire experiment can be ~ e r f o r m e din two 3-h periods of time. Background
The asymmetric reduction of carbonyl compounds by fermenting yeasts i s recognized a s a tool for the preparation of apposite alcohols,' proving more enantioselective than traditional organometallic reducing agents.= Because the central microoraanism i n baker's veast contains a number .. ofoxid~,reductasr~.'a variety ofkctone-:h a w been found to react. One of them is the simple aldrhsde of fermcene, and in this short paper we out~idea sequknce suitable for the undergraduate preparation of ferrocenylmethanol. Experimental
Fleischmann's and Red Star brands of baker's yeast can be purchased a t local groceryor supermarkets. All theother reagents are commercially available. General Procedure Into a l-L round-bottom flask equipped with a magnetic a sucrose. stirrer are olaced 600 mL tap water and 90 Ilaker's yenst t 4 0 g~isadded w ~ t hstirring, whereupon brisk fermentation occurs. The f~!rmentingmixture is iitirred for
10 min, and a solution of ferrocenecarboxaldehyde (3.0 g, 14 mmol) in 6 mL 90% aqueous ethanol i s added portionwise. The mixture is stirred a t room temperature for 24 h. During this time the suspension changes color from orange to yellow. The solution i s then filtered through a pad of Celite, and the filtrate i s extracted with three 30-mL portions of methylene chloride. The methylene chloride extracts are combined and dried over anhydrous sodium sulfate, filtered, and evaoorated to drvness to afford a brown-vellow oil (2.4 g, 8096;. 'XturatioLof the oil with hexane >elds a solid t h a t , w h e n recrystallized from h e x a n e , gives ferrocenylmethanol as golden needles. (In "runs" of two days or longer, one never sees any methylferrocene, but rather some ethyl ether derivative of the alcohol.) Analyses
Femcenylmethanol: m.p. (recrystallized from hexane) 77-78 "C; m.p. benzoyl derivative 124-131 O C ; mixed melting point with known4 ferrocenvlmethanol 77-78 6: PMR 3236, i236, li05,9'89 cm-1 'Sih, C.; Chen, C.; Angew Chem. In!. Ed. Eng. 1984, 23, 570. 2Kagan. H . : Wilkinson, G.: Stone, E. W.; Comprehensive Organometallic Chemistm Pergamon, Oxford. 1982, p 463. 3MacLeod, R.; Prosser, H.; Mosher, H. S. BiochemistIy 1964, 3, R?R
4Broadhead. G. C.; Osgerby, J. M.; Pauson, P. L. J. Chem. Soc. 1958,650.
Volume 68
Number 5
May 1991
427
