Copper‐Catalyzed Asymmetric Allylic Alkylation

Falciola, Caroline A.; Alexakis, Alexandre

doi:10.1002/ejoc.200800025

Cited by 248 publications

(82 citation statements)

References 80 publications

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“…The use of lithium halides as additives in the reaction (Table 1, entries [3][4][5] led to the complete conversion of compound 1 a into mixtures of 2 a and 3 a. Lithium bromide (Table 1, entry 4) was seen to give the best results (a point previously observed by the Evans group [15] ); the reaction being both regio-(2 a/3 a > 2:1) and enantioselective (74 %). The substitution reaction was also found to proceed under the more economical conditions in which 1.5 equivalents of the Grignard reagent, 0.75 equivalents of ZnBr 2 , and 1.5 equivalents of LiBr, compared to that of the substrate 1 a, were used (Table 1, entry 6).…”

Section: Resultsmentioning

confidence: 81%

“…The combined reaction mixture was stirred at RT for 2 min before Et 2 O (10 mL) and a saturated aqueous solution of NH 4 Cl (10 mL) were added to the reaction mixture. The organic layer was washed with brine (10 mL) and water (10 mL), then dried over Na 2 SO 4 and concentrated in vacuo. The crude product was purified on silica gel chromatography column (SiO 2 , pentane, R f = 0.79) to recover products 17 (89 mg).…”

Section: Methodsmentioning

confidence: 99%

“…Despite notable efforts, the use of hard nucleophiles (pK a > 25) with palladium catalysts has given rather limited results, [3] forcing research groups to turn their attention to other metals, such as copper. Since the pioneering work of Bäckvall and co-workers in 1995, [4] this metal has been used to catalytically transfer alkyl Grignard, [4,5] zinc, [6] and more recently aluminium [7] reagents with high regio-and enantioselectivities (Scheme 1). The copper system, however, could not be successfully extended to aryl nucleophiles [2b, 8] and despite the work of many research groups using Co, [9] Ni, [10] Ti, [11] Pd, [12] Rh, [13] or Cu [14] catalysts, there is still no general and efficient system for such a transformation of prochiral allylic compounds.…”

Section: Introductionmentioning

confidence: 99%

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Enantioselective Iridium‐Catalyzed Allylic Arylation

Polet

Rathgeb

Falciola

et al. 2009

Chemistry A European J

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105

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We describe herein the development of the first iridium-catalyzed allylic substitution using arylzinc nucleophiles. High enantioselectivities were obtained from the reactions, which used commercially available Grignard reagents as the starting materials. This methodology was also shown to be compatible with halogen/metal exchange reactions. Its synthetic potential is demonstrated by its application towards the formal synthesis of (+)-sertraline.

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Section: Resultsmentioning

confidence: 81%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Enantioselective Iridium‐Catalyzed Allylic Arylation

Polet

Rathgeb

Falciola

et al. 2009

Chemistry A European J

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105

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“…14,37, 47 The asymmetric induction in the presence of ligand 2 is low (7-11% ee; see Table 4, entries [5][6][7][8]. Interestingly, in this reaction, as in the above allylic substitution of (E) 1,3 diphenylallyl acetate, diamidophosphites 1 and 2 favor the formation of the opposite enantiomers of product 11.…”

Section: Methodsmentioning

confidence: 87%

Palladium-catalyzed allylic substitution assisted by 1,3,2-diazaphospholidine derivatives of (R,R)-N-naphthyltartarimide

et al. 2010

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P,P Bidentate diamidophosphite ligands containing the (3R,4R) 3,4 dioxy 1 (1 naphthyl)pyrrolidine 2,5 dione framework and 1,3,2 diazaphospholidine rings with the ste reogenic P atoms were obtained. The use of these ligands provides up to 85% ee in Pd catalyzed asymmetric amination of (E) 1,3 diphenylallyl acetate and up to 95% ee in its asymmetric alkylation with dimethyl malonate.The preparation of drugs, chemical agents for plant protection, food additives, flavors, and stereoindividual polymers is based on modern approaches to the synthesis of optically pure compounds. One of the leading approach es is asymmetric metal complex catalysis. 1-5 In turn, the activity and stereoselectivity of metal complex catalysts largely depend on the successful strategy of design and synthesis of appropriate chiral ligands, among which phos phorus containing compounds are worth noting. 6,7 Along with classic P,P bidentate phosphines, P,P bidentate phosphite ligands are successfully used because they can simply be prepared from accessible precursors, are inert to oxidants, exhibit pronounced π acidity, and are less ex pensive. 8-14 The main attention of researchers is focused on P,P bidentate phosphites containing 1,3,2 dioxaphos phepine rings based on BINOL, H 8 BINOL, and various 2,2´ dihydroxy 1,1´ biphenyls. 13-22Our investigations deal with the synthesis of various diamidophosphites containing stereogenic P atoms and 1,3,2 diazaphospholidine rings and their use in asymmetric catalytic reactions. 23-28 It should be noted that 1,3,2 di azaphospholidines, including P* chiral ones, are an at tractive group of optically active diamidophosphite ligands. For instance, they have balanced electron characteristics: they are both good π acceptors (because of the accessibil ity of the low energy π* PN orbitals) and good σ donors. Inclusion of a phosphorus atom into the five membered ring makes the ligand more resistant to oxidation and hydrolysis; by widely varying the substituents at the N atoms, one can control its steric and electronic parame ters. 29,30 If the electron donating P atom is asymmetric, this substantially promotes chirality transfer in the key step of the catalytic cycle. 2 In the present work, we report on the synthesis of P,P bidentate diamidophosphites 1 and 2 and their use for enantioselective catalysis (Scheme 1). The 1,3,2 di azaphospholidine rings in these ligands are linked to the sterically rigid tartarimide (3,4 dioxypyrrolidine 2,5 dione) ring. Note that known ligands with the pyrrolidine 2,5 dione fragment L A-C are efficient stereoselectors in Pd catalyzed allylic substitution and Rh catalyzed hydro genation. 31- 33 We tested compounds 1 and 2 in Pd catalyzed asym metric allylation, which is an effective tool for (1) estima tion of the efficiency of novel chiral ligands and (2) stereo selective synthesis of valuable natural compounds. 14,34- 37 We also compared the asymmetry inducing activity of both ligands 1 and 2 themselves and their known analogs L B and L C . Results and DiscussionNovel P,P bidentate ...

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“…[1][2][3][4][5][6] Activity and enantioselectivity of the metal complex catalysts are determined to a great extent by a proper design and synthesis strategy of the corresponding chiral ligands, first of all, phosphorus containing ligands, thousands representatives of which were used in various asymmetric transformations. [1][2][3][4][5][6][7][8][9][10][11][12][13] However, elaboration of an efficient asymmetric inductor for a given catalytic process often represents a challenge. The vast majority of known phosphorus-based chiral ligands in the corresponding metal complexes are able to catalyze (with different enantioselectivities) either a certain type of chemical transformation, or one certain reaction.…”

Section: Introductionmentioning

confidence: 99%