Toluates chirality

Lateral lithiation of (d )-4-isopropyl-2-(o-tolyl)oxazoline and reaction with aldehydes provides the addition products 1148 with moderate to good diastereoselectivity. The addition of TMEDA is vital for any diastereoselectivity to be observed. The major (,S,A)-products lactonize faster under acidic conditions providing dihydroisocoumarins 1149 in up to ee 97% (Scheme 286, Table 53) <2005T3289>. Similarly, the addition of laterally metallated o-toluates to chiral aldehydes provides a key dihydroisocoumarin during a total synthesis of AI-77-B <1999J(P1)1083>. 

Bidentate base. The chiral lithium amide of (S)-l has been used to generate the anion of the ethyl o-toluate 2 and as a chiral complcxing agent in reaction of the anion with acetaldehyde to give optically active mellein methyl ether (3) in 53% optical yield. Optical yields are markedly lower when a chiral base similar to 1 but lacking the OCH, group is used. 

Enantiopure l,2-cis-dihydroxycyclohexa-3,5-diene carboxylic acids have considerable synthetic potential as building blocks in chiral synthesis. Such cis-diols can be produced from benzoic acid derivatives by the action of toluate- 1,2-dioxygenase of Pseudomonas putida mt-2125 or homologous enzymes of a different origin (Fig. 16.6-... 

The methyl o-toluate complex [RuCl2(/i -l,2-MeCgH4C02Me)]2 (1) employed in earlier studies on planar chiral areneruthenium complexes proved to be a suitably labile precursor to the tethered arene complexes. It reacts with the donors mentioned above in a 1 2 mol ratio in dichloromethane at room temperature to give quantitatively the corresponding P-bonded adducts [RuCl2( / -... 

Regan AC, Staunton J (1987) Asymmetiie Synthesis of (-t)-Citiinm Using an Ortho-toluate Carbanion Generated by a Chiral Base. J Chem Soe Chem Commun 520... 

Fractionation of the polymer by solvent extraction, optical rotation ([a]o ) and IR absorption (D763/D732) of the fractions indicated that the more soluble polymer fractions consisted, as expected, of copolymer of (S)-monomers, whereas the last fraction was based on poly[(R)DMO)]. In the presence of the above high yield system, activated by Al(i-Bu)3 and p-methyl toluate (MT) as external base, DM0 and (S)3MP (3.8/1 molar ratio) gave results very similar to the conventional catalysL This indicates that the chiral recognition of active centers capable of polymerizing these sterically hindered branched olefins remains substantially the same even in the presence of the support (MgCl2) and the Lewis base. 

Regan, A.C., and J. Staunton Asymmetric Synthesis of Mellein Methyl Ether Use of or//zo-Toluate Carbanions Generated by Chiral Bases. Chem. Commun. 1983, 764. 

---

See also in sourсe #XX -- [ ]

---