Chiral aryl iodide catalyst

Figure 4.1 Chiral aryl iodide catalysts for enantioselective a-oxytosylation of ketones.

Scheme 23 Stereoselective phenolic dearomatization using chiral aryl iodide catalysts 55...

New chiral aryl iodide catalysts 55 were prepared by Hamerd et al. for assessing the stereoselective phenolic dearomatization. Catalysts 55 derived from 8-iodotetralone and tartaric acid could be used to synthesize enantioenriched para-quinols (up to 60% ee) from phenols as shown in Scheme 23 [73]. 

A new chiral aryl iodide catalyst, derived from 8-iodotefralone and tartaric acid,... 

Higher levels of enantioselectivities in the a-oxytosylation of ketones were achieved in several recent works. Chi Zhang and coworkers have evaluated spirobiindane-based chiral iodoarenes as catalyst and were able to obtain a-tosyloxylated ketones in up to 58% enantiomeric excess using catalyst 12 (Figure 4.1) [28]. Moran and Rodriguez have prepared several chiral aryl iodides (e.g., structures 13 and 14, Figure 4.1) and... 

Chiral aryl iodides containing norephedrine or pseudo-ephedrine moieties such as 10 [27], chiral iodooxazoline catalyst 11 [28] and the spirobiindane scaffold 12 [29] were also proven to have potential towards catalytic asymmetric a-oxytosylation reactions. The best results obtained in terms of enantioselectivity of product 2 using these chiral iodine catalysts are 18% ee (with 10), 48% ee (with 11) and 53% ee (with 12) (Fig. 3). 

Aryl iodides 590 react with nona-1,2-diene in the presence of a palladium catalyst and a chiral bisoxazoline ligand to afford isochromans 591 in good yield with moderate enantioselectivity (Equation 244) <1999JOC7312>. 

Cross-coupling carboamination reactions between allenes and 2-haloaniline derivatives or halogenated allylic amines have also been employed for the generation of substituted indolines, and use of an appropriate chiral catalyst for these transformations leads to formation of enantioenriched products [52]. For example, Larock has described the synthesis of indoline 56 via the Pd-catalyzed reaction of aryl iodide 54... 

Finally, an asymmetric variant of the Suzuki reaction was developed using as catalyst a poly-NHC metal complex with hgand 2 (see also Section 2.1). The complex exhibited a rather low catalytic activity toward aryl iodides and bromides as substrates. However, chiral binaphthyls were prepared with ees up to 70%. ... 

Phosphorylation of At2PH-BH3 with aryl halides proceeds under mild conditions using Pd-Cu catalyst and P-chiral phosphine-boranes of high enantiopurity are prepared by this method. As an effective ligand, MePPh2 is used with Pd(OAc)2. The phosphine-borane 50 was prepared in 68 % yield by phosphorylation of optically active (Sp)-methylphenylphosphine-borane (47) via 48 with the iodide 49 in the presence of the Pd(OAc)2-MePPh2 catalyst and Cul as a cocatalyst at 0°C for 3 days. The reaction proceeded with retention of stereochemistry and the asymmetrically substituted phosphine 51 with 99% ee was obtained [15]. 

---