Approaches to natural-product synthesis with organometallic systems based on iron, molybdenum and manganese

Abstract

New methods for the construction of quaternary carbon centres, with organoiron and organomolybdenum chemistry, are presented. Regiocontrolled addition of tin enolates to substituted cyclohexadienyliron tricarbonyl complexes leads to a new approach to trichothecene synthesis, illustrated by a short total synthesis of ( + )- trichodiene. A new coupling reaction of alkenes and diene-Fe(CO) 3 units is described, the outcome of which is equivalent to a [6 + 2] ene reaction. Some applications of arene-manganese tricarbonyl complexes to the preparation of substituted diaryl ethers are discussed, in the context of synthetic approaches to the glycopeptide antibiotics ristocetin A and vancomycin. Finally, stereocontrolled nucleophilic addition to cycloheptadienyliron complexes is illustrated and applied to a synthesis of the Prelog-Djerassi lactone.

Synthesis and Characterization of Stable Cationic [Hydrotris(1-pyrazolyl)borato]Mo(CO)(NO)(η3-allyl) ComplexesSolid-State and Solution Evidence for an η2-Allyl Structure

“…The use of stoichiometric transition-metal π-allyl complexes for the regio- and stereocontrolled synthesis of organic molecules has garnered considerable attention in recent years. In particular, η 3 -allyl and η 4 -1,3-diene moieties coordinated to molybdenum have been thoroughly investigated. − One specific tactic for activating neutral (η 5 -C 5 H 5 )(π-allyl)Mo(CO) 2 species toward nucleophilic attack involves replacement of a CO ligand with NO + , and this has led to considerable interest in the synthesis, characterization, and reactivity of (η 5 -C 5 H 5 )Mo(CO)(NO)(π-allyl) + complexes. ,− ,,,,− …”

Synthesis of N-(2-Pyranyl)- and N-Cyclohexylindole Derivatives via Stereoselective Addition of Indole Nucleophiles to Organomolybdenum Complexes

“…The utilization of stoichiometric transition-metal π-complexes for the stereocontrolled construction of fairly complex organic molecules , has been demonstrated primarily by Pearson 4 and Liebeskind. , The coordination of a substrate to a metal moiety generally directs all incoming nucleophiles to the face of the π-ligand opposite the metal, an anti -directing effect .…”

Preparation of Dicarbonyl[hydrotris(1-pyrazolyl)borato](η3-allyl)molybdenum Complexes Bearing Electron-Donating Substituents (1-((tert-Butyldimethylsilyl)oxy), 1-Alkoxy, and 1-Acetoxy) via the Nucleophilic Addition of Mo(CO)3(DMF)3 to Enals and Enones

“…η 3 -Allylic complexes of the transition metals are of great use in organic synthesis. − By far the vast majority of those π-allyl complexes that have been studied as stoichiometric reagents possess alkyl, aryl, acyl, and alkoxycarbonyl substituents, there being few general routes to (η 3 -allyl)metal complexes bearing electron-donating substituents. − As part of an ongoing study of the synthesis, properties, and synthetic utility of TpMo(CO) 2 (η 3 -allyl) complexes − (Tp = hydrotris(1-pyrazolyl)borato), , a general preparative route to TpMo(CO) 2 (η 3 -allyl) complexes possessing electron-donating substituents was desired.…”