Hydroxyalkylation, Friedel-Crafts

Gothelf, A. S., Hansen, T., Jorgensen, K. A. Studies on aluminum mediated asymmetric Friedel-Crafts hydroxyalkylation reactions of pyridinecarbaldehydes. J. Chem. Soc., Perkin Trans. 1 2001,854-860. 

Hydroformylation Hydroformylation of the tiyptophan-derived oxazoline 63 led to the formation of tetrahydrocaihazole product 66. In the reaction pathway, P-amidoaldehyde product 64 is initially formed, which is followed by intramolecular Friedel-Crafts hydroxyalkylation to give 65 (Scheme 12.17). 

Supercritical CO turned out to be a benign medium for the Friedel-Crafts hydroxyalkylation of anisole with paraformaldehyde [197]. Thus, the activity of mordenite in sc-CO at 60°C is three times higher compared with the reaction in toluene at 110°C. 

Hydroxyalkyl)porphyrins,84-85 I07b 109 easily accessible from porphyrins by Friedel-Crafts acylation and subsequent reduction, undergo a stereoselective Claisen rearrangement with N,N-dimethylacetamide dimethyl acetal. The substitution pattern and the stereochemical arrangement of the derived chlorins match those of naturally occurring chlorins9 (see Section 1.2.1.2.). 

Other reactions of allyl- and vinyl-phosphine oxides include a detailed study of their intermolecular cyclization by a Friedel-Crafts-type procedure. In certain cases, the unsaturated oxides are generated in situ from /S-hydroxyalkyl(diphenyl)-phosphine oxides. Examples are given in Scheme 12 for the oxides (54)—(56). Control of double-bond position in the products of acid treatment of the oxides (57) has been achieved by using an organosilicon substituent. Thus simple alkyl... 

Different from the hydroxyalkylation reactions using carbonyl compounds as substrates, Nicolaou s and Macmillan s groups developed independently the intramolecular asymmetric Friedel-Crafts-type a-arylation of aldehydes with electron-enriched arenes based on the SOMO activation strategy. Using chiral imidazolidione as catalyst, a series of cyclic aldehydes were obtained in good yields and enantioselectivities with cerium ammonium nitrate (CAN) as single electron transfer oxidant [46]. 

Hydroxyalkylation. Superacid-catalyzed Friedel-Crafts hy-droxyalkylation of aromatics using aldehydes and ketones is a very... 

From the same element group Ga(OTf)3 demonstrated its advantages in several synthetic applications over similar catalysts [1]. Very low catalyst loadings were enough to drive various acid-catalyzed reactions including Friedel-Crafts alkylation, hydroxyalkylation, and acylation... 

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