Friedel-Crafts organocatalytic

General Procedure for Organocatalytic Friedel-Crafts Alkylation of Pyrroles [39]... 

Ouellet SG, Tuttle JB, MacMillan DWC (2005) Enantioselective organocatalytic hydride reduction. J Am Chem Soc 127 32-33 Paras NA, MacMillan DWC (2001) New strategies in organic catalysis the first enantioselective organocatalytic Friedel-Crafts alkylation. J Am Chem Soc... 

Uraguchi D, Sorimachi K, Terada M (2004) Organocatalytic asymmetric aza-Friedel-Crafts alkylation of furan. J Am Chem Soc 126 11804-11805 Uraguchi D, Terada M (2004) Chiral Brpnsted acid-catalyzed direct Mannich reactions via electrophilic activation. J Am Chem Soc 126 5356-5357 Vachal P, Jacobsen EN (2000) Enantioselective catalytic addition of HCN to ketoimines. Catalytic synthesis of quaternary amino acids. Org Lett 2 867-870... 

An enantioselective organocatalytic (with tetrahydro-47/-imidazol-4-one-based catalysts of type 456-HX) Friedel-Crafts alkylation of pyrroles 455 by ot, 3-unsaturated aldehydes generates 3-pyrrolyl carbonyls 457, useful synthons for the construction of a variety of biomedical agents (Equation 108) <2001JA4370, 2002JA1172, 2004ASC1175, 2005JA15051 and references therein>. 

Table 5.9 Organocatalytic Aza Friedel Crafts reaction of furan 45 according to Terada and coworkers [16],...

Interactive mechanism for enantioselective organocatalytic Friedel-Crafts alkylation... 

The Friedel-Crafts reaction of electron-rich aromatic and heteroaromatic compounds with carbonyl acceptors is one of the fundamental reactions for forming carbon-carbon bonds. In recent years, several enantioselective approaches have been described utiMzing copper and scandium complexes as catalysts. In addition, the use of organocatalytic approaches has been considerably expanded. 

Scheme 8.51 Organocatalytic Friedel-Crafts arylations by chiral phosphoric acids.

Scheme 8.52 Organocatalytic Friedel-Crafts arylations of a,P-unsaturated aldehydes.

In 2005, Ricci and coworkers published the first organocatalytic enantio-selective Friedel-Crafts allylation of indoles with nitroalkenes utilising simple thiourea 66. In general, moderate yields and enantioselectivities were observed for this difficult transformation, utilising 20 mol% catalyst... 

The asymmetric Friedel-Crafts alkylation (FC A) is one of the most powerful organic transformations to synthesize optically active aromatic compounds bearing chiral benzylic carbon centers. Since the first example of organocatalytic FCA reaction reported in 2001, continuous interest in this area has resulted in the development of many effective transformations and publications. It s worthy to note that a few important reviews and books have appeared in the literature [1]. This chapter aims to review the progress in the last decade and is organized on the base of different alkylation reagents employed. 

The Pictet-Spengler (PS) reaction is an important method to construct biologically important tetrahydroisoquinoline and tetrahydro- 3-carboline skeletons. Since it represents the intramolecular Friedel-Crafts cyclization of arenes and imines, we cover the asymmetric organocatalytic PS reaction in this chapter [61]. 

In 2009, Nicolaou and co-workers reported an organocatalytic total synthesis of demethyl calamenene (168), a potent cytotoxic agent, which is a beautiful application of SOMO-activated catalysis (Scheme 17.29) [68]. The key step involved an asymmetric intramolecular Friedel-Crafts reaction of aldehyde 166 to achieve the bicyclic aldehyde 167 using imidazolidinone 122 as a SOMO-activated catalyst (56% yield, 90% ee). 

The Banwell group employed an organocatalytic intramolecular Friedel-Crafts cyclization to synthesize the alkaloids (—)-rhazinal (288), (—)-rhazinilam (289), ( )-leuconolam (290), and (-i-)-ep/-leuconolam (291) (261). The spindle toxin (-)-... 

Besides heteroaromatic compounds also electron-rich aromatic compounds like aniline or naphthol derivatives have been employed in organocatalytic Friedel-Crafts reactions (267, 268). Kim et al. demonstrated this in the synthesis of (+)-curcuphenol (294) (267), a bioactive sesquiterpene phenol isolated from the marine... 

Paras NA, MacMillan DWC (2(X)1) New Strategies in Organic Catalysis The First Enantioselective Organocatalytic Friedel-Crafts Alkylation. J Am Chan Soc 123 4370... 

Eey STC, Lear MJ (2010) A Bismuth(m)-Catalyzed Friedel-Crafts Cyclization and Stereocontrolled Organocatalytic Approach to (-)-Plateiisimycin. Org Lett 12 5510... 

A-Sulfinyl aldimines undergo Friedel-Crafts reaction with indoles in up to 99% ee, using a copper(II)-bis(oxazoline) catalyst. An organocatalytic asymmetric aza- 0 Friedel-Crafts alkylation of naphthols with A-sulfonylimines has been developed, giving yields and ees up to 99% 0... 

D. Enders, C. Wang, M. Mukanova, A. Greb, Chem. Commun. 2010, 46, 2447-2449. Organocatalytic asymmetric synthesis of polyfunctionalized 3-(cyclohexenyhnethyl)-indoles via a quadruple domino Friedel-Crafts-type/Michael/Michaehaldol condensation reaction. 

A highly enantioselective organocatalytic Friedel-Crafts aminoalkylation of indoles with in situ generated imines was reported by Zhang s group using a multicomponent approach. Chiral phosphoric acid 121 as an efficient catalyst... 

Riguet reported a methodology involving an enantiose-lective organocatalytic Friedel-Crafts alkylation followed by an Ugi 4-center 3-component reaction [57]. In the first reaction, the Friedel-Crafts reaction, 5-hydroxyfuran-2(5F/)-one (53) was used as an electrophile to alkylate indoles 52 to give the intermediate 54, using a diphenylprolinol silyl ether 56 as catalyst (Scheme 7.22). Then, adducts 54—obtained from Friedel-Crafts reaction—were used in a one-pot manner... 

E.Riguet,7. Org. Chem. 2011,76,8143-8150.Enantioselective organocatalytic Friedel Crafts alkylation reaction of indoles with 5-hydroxyfuran-2(5//)-one access to chiral y-lactones and y-lactams via a Ugi 4-center 3-component reaction. 

For selected pioneering examples, see (a) D. Uraguchi, K. Sorimachi, M. Terada, J. Am. Chem. Soc. 2004, 126, 11804-11805. Organocatalytic asymmetric aza-Friedel-Crafts alkylation of furan. (b) T. Akiyama, H. Morita, J. Itoh, K. Fuchibe, Org. Lett. 2005, 7, 2583-2585. Chiral Br0nsted acid catalyzed enantioselective hydrophosphonylation of imines asymmetric synthesis of a-amino phosphonates. 

Lee S, MacMillan DWC (2007) Organocatalytic vinyl and friedel-crafts alkylations with trifluoroborate salts. J Am Chem Soc 129 15438 15439. doi 10.1021/ja0767480... 

Scheme 19.30 One-pot synthesis of oxy-functionalized heteroaromatic compounds based on combination of organocatalytic Friedel-Crafts-type alkylation and laccase-catalyzed oxidation.

In addition, the asymmetric organocatalytic Friedel-Crafts alkylation of indoles with simple a,(3-unsaturated aromatic ketones was studied by Zhou et al., in 2008. This Michael-type Friedel-Crafts alkylation of indoles was... 

In 2009, Nicolaou et al. reported the asymmetric total synthesis of the antitumour natural product demethyl calamenene based on an enantioselective organocatalytic intramolecular Friedel-Crafts type a-arylation of aldehydes bearing electron-donating groups on their aromatic nucleus. This reaction, catalysed by chiral /err-butyl-3-methyl-5-benzyl-4-imidazolidinone, afforded the corresponding polycyclic products in good to high yields and with excellent enantioselectivities for a broad variety of aldehydes, as shown in Scheme 10.4. 

Duan, G.-J., Ling, J.-B., Wang, W.-P, Luo, Y.-C., Xu, P.-F. (2013). Organocatalytic formal [2-1-2] cycloaddition initiated by vinylogous Friedel-Crafts alkylation enantioselective synthesis of substituted cyclobutane derivatives. Chemical Communications, 49, 4625-4627. 

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