Titanium dimethylamino complexes

Odom applied the titanium dimethylamino complexes as precatalyst in hydroamination of alkynes [307]. The dimethylamino-Ti complexes exhibited different... 

Comparable selectivity can be obtained in the alkylation of ben-zaldehyde 3 with diethylzinc using the titanium TADDOL complex 20 (>99 1 er) or 3-exo-(dimethylamino)isoborneol, 21 (>99 1 er), although both methods employ higher catalyst loadings. While benzaldehyde is illustrative, the substrate scope is equally broad in the case of these two catalysts. 

As the importance of primary amides, Morera and Ortar used hexamethyldi-silazane (HMDS) as a source of ammonia in the carbonylation of aryl iodides and triflates to primary amides (Scheme 2.12) [131]. The desired products were isolated in high yields after hydrolysis. In addition, Indolese et al. reported the efficient aminocarbonylation of aryl bromides with formamide at 5 bar of carbon monoxide. Here, using 4-(dimethylamino)pyridine (DMAP) as a base was the key factor for success [132]. Primary benzamides were also prepared from aryl bromides using CO and a titanium-nitrogen complex in conjunction with NaO Bu [133],... 

Ylides Coordinated to Transition Metals. - Complexes of a-keto-stabilised ylides with early transition metals have been reported by Spannenberg et al The reaction of tetrakis(dimethylamino)titanium(IV) and benzoyltriphenyl-phosphonium bromide (48) produces complex (49) (Scheme 5) whose structure... 

Oguni has reported asymmetric amplification [12] ((-i-)-NLE) in an asymmetric carbonyl addition reaction of dialkylzinc reagents catalyzed by chiral ami-noalcohols such as l-piperidino-3,3-dimethyl-2-butanol (PDB) (Eq. (7.1)) [13]. Noyori et al. have reported a highly efficient aminoalcohol catalyst, 2S)-3-exo-(dimethylamino)isobomeol (DAIB) [14] and a beautiful investigation of asymmetric amplification in view of the stability and lower catalytic activity of the het-ero-chiral dimer of the zinc aminoalcohol catalyst than the homo-chiral dimer (Fig. 7-5). We have reported a positive non-linear effect in a carbonyl-ene reaction [15] with glyoxylate catalyzed by binaphthol (binol)-derived chiral titanium complex (Eq. (7.2)) [10]. Bolm has also reported (-i-)-NLE in the 1,4-addition reaction of dialkylzinc by the catalysis of nickel complex with pyridyl alcohols [16]. 

Three new substituted BINOL ligands, (i )-3-[4,6-bis(dimethylamino)-l,3,5-triazin-2-yl]-l,10-bi-2-naphthol (R)-(72), (i )-3,3 -bis[4,6-bis(dimethylamino)-l,3,5-triazin-2-yl]-l,10-bi-2-naphthol (R)- 73), and 2,4-bis(2,2 -dihydroxy-1,10-binaphthalen-3-yl)-6-(/i-tolyl)-l,3,5-triazine iR,R)-74), have been obtained by directed ort o-lithiation and a Suzuki cross-coupling process (Scheme 10) <2005TA3667>. The titanium complex of (R)-72 was found to be an effective catalyst in the asymmetric addition of diethylzinc to a variety of aromatic aldehydes. 

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