New reactive iron carbonyl reagents for applications in organic synthesis

Abstract

This thesis describes studies on the "New Reactive Iron Carbonyl Reagents for Applications in Organic Synthesis". It comprises of three chapters. Each chapter is subdivided into four parts, namely Introduction, Results and Discussion, Conclusions and Experimental Section along with References. The work described in this thesis is exploratory in nature and the chapters are arranged in the order the investigations were executed. The first chapter describes the investigations on the reactions of alkynes with iron carbonyl species, prepared in situ using Fe(CO)5/NaBH4/CH3COOH and Fe3(CO)12/amine systems. In the introductory section, a brief review on the methods of preparation and synthetic applications of the readily accessible Fe(CO)5, Fe2(CO)9, Fe3(CO)12, Na2Fe(CO)4, HFe(CO)4\ HFe2(CO)8\ [HFe3(CO)u]\ H2Fe(CO)4, H2Fe3(CO)n and the coordinatively unsaturated iron carbonyl species such as "Fe(CO)4", and "Fe2(CO)8" are presented. Previously, it was observed in this laboratory that the reactive iron carbonyl species, prepared using the HFe(CO)47RX (RX - CH3I or Me3SiCl) combination, on reaction with alkynes followed by CuCl2.2H2O oxidation gives cyclobutenediones in moderate to good yields. The U.V spectra recorded for the iron carbonyl species, prepared using the Fe(CO)5/NaBH4/CH3COOH and the NaHFe(CO)4/RX (RX - CH3I, CH2CI2 and Me3SiCl) reagent combinations, exhibit characteristic X ^ in solution in the region reported for [HFe3(CO)n]7H2Fe3(CO)ii species. The reaction of alkynes with the iron carbonyl species [HFe3(CO)n]\ prepared in situ by the reduction of Fe(CO)s using NaBH* in the presence of excess CH3COOH in THF, gives the corresponding cyclobutenediones in good yields (60- 73%) after CuCl2.2H2O oxidation (Scheme 1).