Triflates coupling with

Under the same conditions, aryl triflates couple with arylboronic acids to form biphenyls.2... 

Coupling of vinyl triflates with organotins. Vinyl triflates couple with organotin reagents in the presence of catalytic amounts of Pd(0) and lithium chloride (2 equiv.). The reaction is general, but is particularly useful for stereoselective synthesis of 1,3-dienes. ... 

Aryl Grignard reagents usually give better yields in these reactions than alkyl Grignard reagents. Aryl triflates couple with arylmagnesium halides in the presence... 

Enol triflates couple with die allyl or benzyl Grignard reagent in the presence of Li2MnCl4 as a catalyst to give coupling products in high yields (equation 59). Enol triflates can be alkylated with alkylzinc ... 

Like most aryl halides, furyl halides and furyl triflates couple with a var iety of organos-tannanes including alkenyl, aryl, and heteroaryl starmanes in the presence of catalytic palladium. Carbamoylstannane 122 is prepared by treating lithiated piperidine with carbon monoxide and tributyltin chloride sequentially. The Stille reaction of 122 and 3-bromofuran then gives rise to amide 123 [116]. In another example, lithiation of 4,4-dimethyl-2-oxazo-line followed by quenching with Me,SnCl results in 2-(tt ibufylstannyl)-4,4-dimethyl-2-oxa-zoline (124) in 70-80% yield [117]. Subsequent Stille reaction of 124 with 3-bromofuran affords 2-(3 -fuiyl)-4,4-dimethyl-2-oxazoline (125). 

Vinyl triflates couple with Michael acceptors in the presence of triethylamine and palladium catalysts (Scheme 35). The reaction conditions are mild enough so that even acrolein gives good yields without significant polymerization. 

Aryl halides react with a wide variety of aryl-, alkenyl- and alkylstan-nanes[548-550]. Coupling of an aryl tritlate with an arylstannane is a good preparative method for diaryls such as 688. The coupling of alkenylstannanes with alkenyl halides proceeds stereospecifically to give conjugated dienes 689. The allylstannane 690 is used for allylation[397,546,551-553]. Aryl and enol triflates react with organostannanes smoothly in the presence of LiCl[554]. 

The coupling of the enol triflate 703 with the vinylstannane 704[397] has been applied to the synthesis of glycinoeclepin[576]. The introduction of a (Z)-propenyl group in the / -lactam derivative 705 proceeds by use of tri-2-furylphosphine[577]. However, later a smooth reaction to give the propenyl-iactam in 82% yield was achieved simply by treating with Pd(OAc)2 in NMP or CH2CI2 for 3-5 min without addition of LiCI and the phosphine ligand[578]. 

Tandem cyclization/3-substitution can be achieved starting with o-(trifluoro-acetamido)phenylacetylenes. Cyclization and coupling with cycloalkenyl trif-lates can be done with Pd(PPh3)4 as the catalyst[9]. The Pd presumably cycles between the (0) and (II) oxidation levels by oxidative addition with the triflate and the reductive elimination which completes the 3-alkenylation. The N-protecting group is removed by solvolysis under the reaction conditions, 3-Aryl groups can also be introduced using aryl iodides[9]. 

Vinylation can also be done by Pd-catalysed cross-coupling in which one component is used as a halide or triflate and the other as a stannane (Stille reaction) or boronic acid (Suzuki reaction). Entry 9, Table 11.3, is an example of the use of a vinylstannane with a haloindole. lndole-3-boronic acids, which can be prepared by mcrcuration/boration, undergo coupling with vinyl triflates (Entry 10). 

The Stille coupling of an aryl triflate normally calls for the addition of at least one equivalent of LiCl. Presumably, the transmetallation is facilitated by replacing triflate with CP at the palladium intermediate generated from oxidative addition. As Stille demonstrated in 1988, 4-quinolinyl triflate 100 was coupled with phenylstannane 101 in the presence of Pd(Ph3P)4 and LiCl in refluxing 1,4-dioxane to furnish biaryl 102, which was used as an intermediate for the first total synthesis of antibiotic amphimedine (88JA4051). 

Larhed et al. investigated enantioselective Heck reactions with 2,3-dihydrofuran as alkene [86]. In the coupling with phenyl triflate, conditions previously reported by Pfaltz [87] were attempted under microwave irradiation. Interestingly, the catalytic system Pd2(dba)3/(4S)-4-t-butyl-2-[2-(diphenylphosphanyl)phenyl]-4,5-dihydro-l,3-oxazole, identified by the Swiss team, was found suitable for high-temperature microwave-assisted enantioselective Heck reactions (Scheme 76). Using a proton sponge as a base and benzene as a solvent gave the best conversions (Scheme 76). At tempera-... 

Haloalkynes (R—C=C—X) react with ArSnBu3 and Cul to give R—C= C—Ar. Acetylene reacts with two equivalents of iodobenzene, in the presence of a palladium catalyst and Cul, to give 1,2-diphenylethyne. 1-Trialkylsilyl alkynes react with 1-haloalkynes, in the presence of a CuCl catalyst, to give diynes and with aryl triflates to give 1-aryl alkynes. Alkynes couple with alkyl halides in the presence of Sml2/Sm. Alkynes react with hypervalent iodine compounds " and with reactive alkanes such as adamantane in the presence of AIBN. ... 

ArSnRs, and with arylmercury compounds. Aryl triflates react with arylbo-ronic acids ArB(OH)2, or with organoboranes, in the presence of a palladium catalyst, to give the arene in what is called Suzuki couplingCyclopropyl groups can be attached to aromatic rings by this reaction. Even hindered boronic acids give good yields of the coupled product. 

Stannyl derivatives of 2ff-pyran-2-one, accessible from bromopyranones by cross coupling with organotin reagents, themselves take part in Pd(0)-catalyscd cross coupling with enol triflates. This methodology offers a new approach to steroidal pyran-2-ones <96JOC6693>. 

Coupling with Aryl and Vinyl Halides and Triflates... 

Triflates prepared from (V-alkoxyearbonyl lactams can be coupled with aryl and alkenylboronic acids.227... 

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