Lawrence F. Kelly

The first full resolution of 2-methoxytricarbonylcyclohexadienyliron hexafluorophosphate, an example of a synthetic organic equivalent in the series of chiral cyclohex-2-enone-4-cations.

Abstract A superior method, using Hunig base in CH2Cl2, converts complexed cations of type (1) into type (2) by the action of nucleophiles HXR′, and permits the optical resolution of the title salt via the ethers of (2,R=Ome,R′ = (−)-menthoxy).

Organometallic compounds in organic synthesis—XI

Abstract The concept is discussed of superimposed lateral control of reactivity, stereochemistry and structures, by attachment of complexed metal atoms to olefinic systems. This differs from classical endogenous control of synthesis by classical anionoid and cationoid groups in the skeleton, and its application has many theoretical and practical advantages. It is illustrated by considerations of reactions of substituted tricarbonylcyclohexa-l,3-dieneiron derivatives; notably the derived dienyliron salts, which are defined as equivalents of specifically substituted aryl cations or as cyclohex-2-enone cations, dependent on the structures and reaction sequences. The effects are noted of classical substituents on the positions and on the rates of reactivity of some complexed dienyl cations ; both regio- and stereospecificities are dependent on the nature of the anion involved and the conditions. Probable mechanisms are discussed. Other effects of lateral control include those on the classical reactivities of attached groups (such as hydrolysis of CO2Me) and on adjacent groups, such as stereochemistry of reduction of the 3-carbonyl in the ergosterone complex. Some useful new C-C bond-forming reactions made possible by the approach are noted.

Organometallic compounds in organic synthesis: reactions of some tricarbonylcyclohexadienyliumiron complexes with 1,2-bis(trimethylsiloxy)-1-cyclopentene. A novel route to 2-(substituted)-2-cyclopenten-1-ones.

Abstract 1,2-Bis(trimethylsiloxy)-1-cyclopentene reacts with a range of tricarbonylcyclohexadienyliumiron cations to give initially siloxy acyloins, treatment of which with MeOH-HCl gives the 2-(substituted)-2-cyclopenten-1-one in good yields (56–78%).

Organometallic compounds in organic synthesis : electrophilic reactions of some tricarbonylcyclohexadienylium-iron complexes with allyltrimethyl silanes.

Abstract Allyltrimethylsilanes react with a range of tricarbonylcyclohexadienyl-iron complexes under mild conditions to form new carbon-carbon bonds in excellent yields.

Lateral control of skeletal rearrangement by complexation of thebaine with Fe(CO)3

Abstract Temporary attachment of Fe(CO) 3 to thebaine allows access to northebaine, 14α-substituted thebainone derivatives, and a rearranged codeinone analogue lacking the oxide ring and in which the dihydrophenanthrene nucleus is replaced by a dihydrofluorene one.

Organometallic compounds in organic synthesis. An equivalent of aromatic nucleophilic substitution by reactions of tricarbonylcyclohexadienyliumiron salts with O-silylated enolates: a novel arylation in the 2-position of carbonyl compounds.

Abstract Tricarbonylcyclohexadienyliumiron salts are synthetically equivalent to specifically substituted phenyl cations.

Organometallic compounds in organic synthesis: XVIII. Removal of OMe from some substituted tricarbonylcylohexadieneirons to form substituted tricarbonylcyclohexadienyliron salts

Abstract The structure of tricarbonylcyclohexadienyliron salts resulting from the action of acids on 1- or 2-OMe derivatives of the tricarbonylcyclohexadienerion series indicate the operation of two alternative processes for removal of OMe. The major one results in a mesomeric cation complex with the complexed system terminating at the carbon initially carrying OMe. The minor process results in a system terminating at the adjacent carbon. The labelling introduced by the use of deutero-acid relates the initial stages to the Fe-mediated protonations involved in the catalysed rearrangements of such complexes. In the 1-Ome series deuterium is found at the 1-position; in the 2-OMe series a β-D is introduced. Evidence from D-labelled precursors is adduced that in the 2-OMe series there is transfer of H (or D) across the β-face from the 5-position to the 2-position, in permiting cation formation.

Replacement of CO by R3P in the cyclohexa-1,3-dienetricarbonyliron series

Abstract Reaction of tricarbonylcyclohexa-1,3-dieneiron complexes with trimethylamine-N-oxide in the presence of trivalent phosphorus donor ligands gives the corresponding (R3P)(OC)2Fe(cyclohexa-1,3-diene).

Organometallic compounds in organic synthesis: reactions of some tricarbonylcyclohexadienylium-iron complexes with trimethylislyl enol ethers

Abstract O-Silylated enolates derived from ketones react with tricarbonylcyclohexadienyl-iron cationic complexes under very mild conditions to form carbon-carbon bonds in excellent yields.

Organometallics in organic synthesis:tricarbonyl-(3-methoxycyclohexa-2,4-dien-1-yl)-iron(1+). A synthetic equivalent of the C-5 cation of cyclohexenone.

Tricarbonyl-(3-methoxycyclohexa-2,4-dien-1-yl)-iron(1+) PF6(1-) 2 reacts with a variety of nucleophiles to give 5-substituted cyclohex-2-enones. 2 is shown to be a useful precursor for a convergent synthesis of 5-substituted cyclohex-2-enones and to be synthetically equivalent to the 5-cyclohex-2-enone cation 1.