Aryl Inflates

Aryl fluorosulfonates have recently been reported as less expensive alternatives to aryl inflates. Compound 3 has been synthesized in 50% isolated yield using 4-nitrophenyl fluorosulfonate as the electrophilic partner in the cross-coupling reaction. Roth, G. R. Fuller, C. E. J. Org. Cham. 1901,56,3493-3496. 

Palladium-Catalyzed Reduction of Vinyl and Aryl Inflates... 

In a series of studies, Shibasaki examined the formation of chiral benzylic quaternary centers by using asymmetric intramolecular Heck reactions. The effect of double-bond stereochemistry was examined in the cyclization of aryl Inflates 9.1 and 9.3 (Scheme 8G.9) [22], As is commonly... 

The coupling of enolisable ketones and aryl halides, despite its great synthetic importance, has been less explored. We recently reported on a very efficient system for the arylation of ketones with aryl halides and triflates using 2 as precatalyst. Aryl inflates are a very attractive alternative to aryl halides, as they can be easily synthesized from readily available phenols. Some examples of suitable substrates for this reaction are presented in Table 14.2. The use of 1 for this reaction has also been performed in large-scale reactions with very good results (Table 14.2, entries 6 and 1)P... 

Coupling of aryl O-carbamates and aryl Inflates with RMgCl. This coupling can be effected by catalysis with Ni(acac)2. The particular value of this coupling is that O-carbamates can direct ort/romctalation, and thus can be converted into useful derivatives for coupling to complex substituted arcncs. 

Synthesis ot aryl ketones or aldehydes from aryl Inflates or iodides and organo stannanes in the presence of CO and a palladum catalyst... 

Allyl, Benzyl, and Related Tins. Simple allyltrialkyltins may couple with acid chlorides, aryl halides, or aryl Inflates to give the allylation product in good yield. Subsequent works revealed, however, that the reaction takes place at either the a or y position, depending on the structure of the tins and the conditions used. At present, the regiochemistry of the coupling is still unpredictable. Moreover, allylic double bonds tend to move into conjugation, when acyl halides and aryl triflates are used as electrophiles. This can sometimes be suppressed by lowering the reaction temperatures. ... 

Common organic functionality such as Lewis basic phenol 3, acid-labile acetal 4, highly reactive aryl inflate 6," and depsipeptide 5 are well-tolerated under the mild reaction conditions (Figure 2). In all cases the products are isolated as one regioisomer and olefin isomer after column purification. 

Ishiyama T, Itoh Y, Kitano T, Miyaura N (1997) Synthesis of Arylboronates via the Palladium(0)-Catalyzed Cross-Coupling Reaction of Tetra(alkoxo)diborons with Aryl Inflates. Tetrahedron Lett 38 3447... 

Mosleh and Inland have established that the oxidative addition of aryl Inflates (At0S02CT3) to Pd°(PPh3)4 gives in DMF the cationic complex rrans-ArPd(DMF)L2+ as characterized by condnctivity measurements (Scheme 1.17a) [35,36], When the same reaction is performed from Pd (PPh3 >2 (OAc) generated from Pd(OAc>2 and 3 equiv PPh3, the neutral complex rrans-ArPd(OAc)L2 is formed in equilibrium with the cationic complex (Scheme 1.17b) [37]. This again emphasizes the important role of acetate ions delivered by the precursor Pd(OAc)2. 

In 1990, Cabri el al. [40a] reported that the precursor Pd(OAc>2 associated with a biden-tate P P ligand as dppp (1,3-bis-diphenylphosphinopropane) appeared to be more efficient than PPhs in Mizoroki-Heck reactions performed from aryl Inflates and enol ethers (electron-rich alkenes) moreover, the regioselectivity in favour of the a-arylated alkenes was improved to 100%. Since that time, dppp associated with Pd(OAc)2 has been used extensively to catalyse Mizoroki-Heck reactions and to investigate the factors that control the regioselectivity [Ig, 40]. The chiral bidentate (7 )-Binap (2,2 -bis(diphenylphosphino)-1,1-binaphthyl) associated with Pd(OAc)2 has also been used by Shibasaki and coworkers [2b,d,41a] and Overman andPoon [41b] in intramolecular enantioselective Mizoroki-Heck reactions (also, see Link [2f] for an authorative review on the Overman-Shibasaki chemistry), as well as by Hayashi and coworkers [2a, 41c,d] to control the regioselectivity and enantioselectivity of intermolecular Mizoroki-Heck reactions performed from cyclic alkenes (see Schemes 1.3 and 1.2 (Z = O) respectively). 

Scheme 15.8 Asymmetric Mizoroki-Heck reaction of 2,3-dihydrofuran (39) with various aryl inflates 38.

A cationic Tr-complex is formed when aryl Inflates are employed with dppp, ° a strongly coordinating difunctional phosphine (Scheme 11). Thus, ionization occurs by dissociation of the weakly coordinating triflate counterion.t Alternatively, a neutral rr-complex is generated after phosphine dissociation of one of the arms of a bidentate ligand (Scheme 12). ... 

Figure 11.4 Pd-catalyzed fluorination of aryl Inflates in a CsF packed-bed microreactor — influence of reaction temperature. (Reproduced with permission from Ref [22]. Copyright 2011, Wiley-VCH VerlagCmbH.)...

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