Allylic complexes

Allyl Complexes. Allyl complexes of thorium have been known since the 1960s and are usually stabilized by cyclopentadienyl ligands. AEyl complexes can be accessed via the interaction of a thorium haUde and an aHyl grignard. This synthetic method was utilized to obtain a rare example of a naked aHyl complex, Th(Tj -C2H )4 [144564-74-9] which decomposes at 0°C. This complex, when supported on dehydroxylated y-alumina, is an outstanding heterogeneous catalyst for arene hydrogenation and rivals the most active platinum metal catalysts in activity (17,18). 

Reaction of [Pd(acac)(r -allyl)] (allyl = C3H5, C4H7) with [PdCl2(Hpz)2] provides the homotrinuclear complexes [(/ -allyl)Pd(/LA-Cl)(/LA-pz)Pd(/A-Cl)(/LA-pz) Pd(r -allyl)] (79CJC3237). Further reaction with pyrazolate anion yields [(r -allyl)Pd(/A-pz)2Pd(/x,-pz)2Pd(r -allyl)]. 

Thorium carbides, 24 761, 4 689—690 Thorium carbonate, 24 765 Thorium carboxylates, 24 768-769 Thorium chlorides, 24 762-763 Thorium complexes allyl, 24 773... 

A Hylic sulfones (cf., 9, 132). In the presence of this Pd(0) complex, allylic acetates condense with sodium p-tolylsulfinate to form allylic sulfones (predominately E). The more substituted isomer is formed initially, but rearranges after extended reaction time to the more stable allylic sulfone.22... 

ChloroaUylation. In the presence of this Pd(II) complex, allylic chlorides react with alkynylsilanes to form (E)-4-trimcthylsilyl-5-chloro-1,4-dienes in yields of 80-OV1,.- ... 

Contrary to what is observed during tandem addition reactions to [Os]-toluene (vide supra), electrophilic additions to [Os]-bound ortho- and meta-xylenes result in regioselective attack at C6 (Table 3). A coordination isomer having the metal across C4-C5 (19) is the only isomer observed for both ortho- and meta-xylene. Electrophilic addition of HOTf (entry 1) or dime-thoxymethane (entries 2 and 3) at C6 generates the complexed allyl cation 20, which can be trapped with MMTP to form the complexed diene 21. Demetalation using AgOTf releases the free diene 22, which potentially possesses two adjacent quaternary centers (entry 3) [15]. 

Work in this area has also focused on optically active complexes. Exchange of vinyl ether complex (94) with optically active alcohols gives unequal mixtures of diastereomeric vinyl ether complexes in the best case, (-)-menthol gives a 4 1 mixture emiched in (99). Optically active epoxides are capable of affording enantiomerically pure complexes allylic alcohol substituents allow reversible conversion to the related lactone complexes (100) (equation 21). 

Chemistry of coordination complexes and organometallic compounds. Allyl and enyl complexes Allyl-transition metal systems... 

In the laboratory of J.H. Rigby, synthetic studies were undertaken on the ingenane diterpenes. During these studies, it was necessary to investigate the ring opening reactions of a structurally complex allylic epoxide intermediate. This allylic epoxide was prepared from a 1,3-diene in three steps dihydroxylation, epoxidation and Corey-Winter olefination. 

Silver complexes Allylation, The f-,3-pentadiene with al BINAP-AgOTf complex... 

Keywords C-0 bond cleavage, Activation of C-0 bonds, Oxidative addition, Transition metal complexes, Allylic compounds, Esters, Ethers, Anhydrides, Alcohols... 

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