Über enolisierte Derivate der Chlorophyllreihe. 132-Desmethoxycarbonyl-173-desoxy-132,173-cyclochlorophyllid a-enol und eine Methode zur Einführung von Magnesium in porphinoide Ligandsysteme unter milden Bedingungen. (Vorläufige Mitteilung)

Enol derivatives in the chlorophyll series. 13²-Desmethoxycarbonyl-17³-desoxy-13²,17³-cyclochlorophyllide a-enol and a method for the introduction of magnesium into porphinoid ligands under mild conditions Magnesium transfer from the iodo-magnesium salt of 3,5-di-t-butyl-4-hydroxy-toluene (BHT) into methyl pheophorbide a is a fast process in methylenechloride/ether solution at ambient temperature. This procedure for the introduction of magnesium into labile chlorin ligands has made possible the preparation of a crystalline 13², 17³-cyclochlorophyllide a-enol. Concomitant use of the lithium salt of BHT facilitates the more critical insertion of magnesium into methyl bacteriopheophorbide a. The preparative success of these magnesium transfers depends crucially upon the solvent system used. Under conditions where the complexation of methyl pheophorbide a with iodo-magnesium-BHT is essentially complete within 2 minutes at 12° in methylenechloride/ether solution, strong inhibition of the magnesium transfer is observed by cosolvents such as pyridine, dimethylacetamide, dioxan or tetrahydrofuran.     

N‐Functionalized Ferrocenes: Subvalent Group XIV Element Chlorides and tert‐Butyllithium‐Induced C−C Bond Cleavage under Mild Conditions

The ferrocene derivative (η⁵‐Cp)Fe{η⁵‐C₅H₃‐1‐(ArNCH)‐2‐(CH₂NMe₂)} ( 1 ; Ar=2,6‐iPr₂C₆H₃)) reacts diastereoselectively with LiR by carbolithiation and subsequent hydrolysis to give (η⁵‐Cp)Fe{η⁵‐C₅H₃‐1‐(ArHNCHR)‐2‐(CH₂NMe₂)} ( 3 : R=tBu; 4 : R=Ph; 5 : R=Me) in high yields. For R=tBu, the organolithium derivative (η⁵‐Cp)Fe{η⁵‐C₅H₃‐1‐(ArLiNCHR)‐2‐(CH₂NMe₂)} ( 2 ) was isolated. Compound 2 reacts with GeCl₂?dioxane and SnCl₂ to give the metallylene amide chlorides (η⁵‐Cp)Fe{η⁵‐C₅H₃‐1‐(ArMNCHtBu)‐2‐(CH₂NMe₂)} 6 (M=GeCl) and 7 (M=SnCl), respectively, which each contain three stereogenic centers. The potential of 7 as a ligand in transition‐metal chemistry is demonstrated by formation of its complex (η⁵‐Cp)Fe{η⁵‐C₅H₃‐1‐(ArMNCHtBu)‐2‐(CH₂NMe₂)} [ 9 , M= Sn(Cl)W(CO)₅]. Treatment of 3 with tert‐butyllithium at room temperature causes an unprecedented carbon–carbon bond cleavage whereas under kinetic control, lithiation at the Cp‐3 position takes place, which leads to the isolation of (η⁵‐Cp)Fe{η⁵‐C₅H₃‐1‐(ArHNCHtBu)‐2‐(CH₂NMe₂)‐3‐SiMe₃} ( 10 ).