LiAl OC

An even more interesting result, recently obtained with LiAl[OC(Ph)(CF3)2]4 (107), is applicable to similar allylic substitutions. Reagent 107 is readily prepared by treatment of a toluene suspension of LiAlH4 with 4 equiv. HO-C(Ph)(CF3)2 under reflux conditions. The X-ray crystal structure of 107 shows that the lithium is hexa-coordinated with two internal oxygen and four internal fluorine atoms. By use of 10 mol % 107, cyclohexenyl acetate 108 and Si-3 were coupled successfully to furnish 109 in 92 % yield (Sch. 51) [100]. 

Very recent applications of the reagent LiAl[OC(Ph)(CF3)2]4 (107) in conjugate additions have been described (Sch. 62). The capacity of 107 to catalyze sterically demanding additions in toluene obviates the necessity of using either highly polar media (5.0 m LPDE) or ultra high pressure [100]. 

Conjugate additions. Efficient reaction between silyl ketene acetals and conjugated carbonyl compounds in nonpolar aprotic solvents (such as toluene, while containing TMEDA) is possible when catalyzed by LiAl[OC(CF3)2Ph]. The catalyst is derived from LiAlH and HOC(CF3)2Ph. 

Grieco et al. and Ghosez et al. [25] have recently reported that lithium trifluorometha-nesulfonimide (LiNTf2) in acetone or diethyl ether is a safe alternative to lithium perchlorate solutions for effecting Diels-Alder and hetero-Diels-Alder reactions. In addition, the lithium salt of tetrakis(polyfluoroalkoxy)alu-minate (LiAl(OC(Ph)(CF3)2)4) was described, a new hydrocarbon-soluble catalyst, for carbon-carbon bond-forming reactions like the... 

Catalytic version of this allylic substitution is performed with LiCo(B9C2Hn)2 and LiAl((OC(Ph)(CF3)2)4. LiCo(B9C2Hn)2 is a novel Lewis acid that would have... 

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