Titanium—iron bonds reactions with

In order to overcome the poor electrophilicity ofimines, nitrones arc used as partners for reaction with iron acyl enolates 428. Benzaldehyde phenylnitrone (5) reacts rapidly with the aluminum-based enolate at —78 C to give a crude /J-hydroxyamino iron acyl 6 (68% yield). Treatment with aqueous titanium trichloride in tetrahydrofuran at room temperature causes a selective reduction of the N—O bond and affords the /1-amino iron acyl 7 with inverse configuration compared to the addition ofimines (99% yield d.r. 11 23). 

Bonding is used extensively on steel. The reaction occurs with a high hydrogen dilution of the BCI3 to prevent substrate attack. An iron boride is formed. 1 1 Not all metals, however, are suitable to bonding. For instance, the bonding of titanium by CVD in a chloride-based system is more difficult since the titanium substrate is highly susceptible to HCl attack and the rate of diffusion is low. 

Addition of an T -allyl-Fp complex to this compound affords an T -aIlyl-Fp-substituted cycloheptatriene system. Two double bonds are involved in an (T -diene)iron complex. The remaining free double bond of the silyl enol ether attacks as a nucleophile at the cationic r -alkene-Fp moiety to form an (Tj -diene)iron complexed cyclopentane annulated cycloheptadienone. Treatment with CAN in methanol under carbon monoxide atmosphere releases the methoxycarbonyl-substituted free ligand (Scheme 4-25). Reaction of the Ti -dienyliumiron intermediate of Scheme 4-25 with an ( , Z)-isomeric mixture of ri -crotyl-Fp proceeds with high diastereoselectivity. Four new stereogenic centers are formed in the course of this formal [3+2] cycloaddition. A hetero [3+2] cycloaddition is also feasible between T -ailyl-Fp complexes and aromatic aldehydes in the presence of zinc chloride or titanium(IV) chloride to provide tetrahydrofuran derivatives (Scheme 4-26). A 1,2-shift of the iron complex fragment occurs in the course of this reaction. Employment of imines affords the corresponding pyrrolidines. ... 

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