Proline-Based P, N Ligands in Asymmetric Allylation and the Heck Reaction

Gilbertson, Scott R.; Xie, Dejian; Fu, Zice

doi:10.1021/jo0158231

Cited by 66 publications

(24 citation statements)

References 36 publications

(40 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The ee of the major thermodynamic isomer 24 was found to be quite low (20%) although interestingly a higher ee of the minor regioisomer 23 was observed (34%, entry 2). Application of ligand 9 proved again to give low yields ranging from 26-9% of the thermodynamic regioisomer 24 but gave higher ees than for the corresponding phenylations in all cases (entries [4][5][6]. Triethylamine was found to be the base of choice, giving the highest ee and yield with this particular ligand (49% yield of 24 and 61% ee, entry 4).…”

Section: Asymmetric Cyclohexenylation Of 23-dihydrofuran (1)mentioning

confidence: 85%

“…The enantioselectivities were also good ranging from 68-77% (entries 1-3). The i-Pr-substituted ligand 8 was found to give lower yields (23-46%), although with higher ees of 70-89% (entries [4][5][6]. The use of diisopropylamine as base gave the optimum result of 33% yield and 87% ee although proton sponge gave a slightly higher ee of 89% but a considerably lower yield of 23%.…”

Section: Asymmetric Phenylation Of 23-dihydrofuran (1)mentioning

confidence: 97%

See 1 more Smart Citation

The Application of HETPHOX Ligands to the Asymmetric Intermolecular Heck Reaction

Kilroy¹,

Cozzi²,

End³

et al. 2004

Synlett

View full text Add to dashboard Cite

Two new heterocyclic diphenylphosphinooxazolines derived from thiophene and benzothiophene were prepared in moderate to good yield and these, and a range of related HETPHOX ligands, were applied in the intermolecular asymmetric Heck reaction. Phenylation of 2,3-dihydrofuran with the t-butyl-substituted thiophene-oxazoline ligand gave (R)-2-phenyl-2,3-dihydrofuran highly regioselectively with excellent enantioselectivity (91-95% ee) and in good yields (70-97%). In addition, cyclohexenylation of 2,3-dihydrofuran proceeded with enantioselectivities of up to 97% ee in excellent (97%) yields, again with the t-butyl-substituted thiophene-oxazoline ligand proving optimal over a range of reaction conditions investigated.The Heck reaction is the palladium(0) catalysed coupling of an aryl or alkenyl halide with an alkene and has proven to be a highly versatile procedure for C-C bond formation. 1 Since the first enantioselective intermolecular Heck reactions by Hayashi, 2 several new chiral ligands have been developed and employed successfully. 3 The first use of P,N ligands in this reaction was reported by Pfaltz in 1996 who described the arylation and cyclohexenylation of 2,3-dihydrofuran (1), Scheme 1. 4 In contrast to the regioisomer problem encountered by Hayashi who formed both the kinetic and thermodynamic products 2 and 3, the application of palladium complexes of diphenylphosphinooxazoline ligands 4 produced only (R)-2 in 97% ee.Since that study a range of oxazoline-containing ligands have been applied to this reaction by the groups of Gilbertson, Hashimoto, and Hou with similar high levels of regioselectivity and enantioselectivities. [5][6][7][8][9] We also reported the application of diphenylphosphinoferrocenyloxazoline ligands which gave (R)-2 in moderate to good yields of up to 72% with good regioselectivity for phenylations with consistently high ees of up to 99%, while cyclohexenylations gave the related cyclohexenylated kinetic isomer in moderate to good yields of up to 75% and good ees up to 85%. 10 We subsequently extended the application of diphenylphosphinoaryloxazolines to intermolecular Heck reactions employing 2,2-dialkyl-2,3-dihydrofurans as substrates 11 and to the asymmetric intramolecular Heck reaction. 12 Related (phosphinophenyl)benzoxazine ligands from Kündig and Meier and iso-PINPHOS ligands from Kocovsky followed the same pattern of both high regioselectivity and enantioselectivity in the intermolecular Heck reaction. 13,14 The ligand used in the first example of the asymmetric intermolecular Heck reaction by Hayashi was the axially chiral diphosphine ligand, BINAP. This was the ligand of choice for many subsequent studies but a more recent related axially chiral example by Tietze, the thiophene containing ligand BITIANP, showed higher selectivity and reactivity. 15 In 2002, the same group subsequently reported the synthesis of novel chiral thiophene-, benzothiophene-and benzofuran-oxazoline ligands 5-10 and their application to palladium catalysed allylic allylations. 16 These ligands diffe...

show abstract

Section: Asymmetric Cyclohexenylation Of 23-dihydrofuran (1)mentioning

confidence: 85%

Section: Asymmetric Phenylation Of 23-dihydrofuran (1)mentioning

confidence: 97%

The Application of HETPHOX Ligands to the Asymmetric Intermolecular Heck Reaction

Kilroy¹,

Cozzi²,

End³

et al. 2004

Synlett

View full text Add to dashboard Cite

show abstract

“…[107] It is unusual in that the enantioselection is determined by the configuration at the pyrrolidine ring rather than at the oxazoline.…”

Section: Reviewmentioning

confidence: 99%

The Development of Bidentate P,N Ligands for Asymmetric Catalysis

2004

View full text Add to dashboard Cite

In this review, an attempt is made to systemise the ro √ le which bidentate phosphinamine (P,N) ligands play in asymmetric catalysis. The ligands will be classified, not by the reaction to which their metal complexes have been applied, but by the nature of their donor atoms. In this manner the development of ligand architectural design can be more easily monitored. The asymmetric transformations to which metal complexes of these ligands have been applied include among others, palladium-catalysed allylic substitutions, copper-catalysed 1,4-additions to enones and rhodiumcatalysed hydroboration of vinylarenes. Excellent enantioselectivities, regioselectivities and reactivities have been achieved in each of these processes.

show abstract

“…Alternatively, compound 2 was treated with amino acid methyl ester hydrochloride and catalytic amount of DMAP, and then 3 were obtained as a major product, which can be easily purified by chromatography. Attempt to prepare 3 by treatment of 1 with amino acid methyl ester hydrochloride in the presence of HOBt and EDC also failed [8]. Compound 3 was then selectively reduced to 4 quantitatively by Ca(BH 4 ) 2 prepared in situ using CaCl 2 and NaBH 4 in THF and EtOH [9].…”

Section: Synthesis Of Chiral Bis(oxazoline) Ligandsmentioning

confidence: 99%

Novel bis(oxazoline) ligands derived from camphoric acid for Cu-catalyzed asymmetric cyclopropanation

Tan¹,

Wen²,

Li³

et al. 2005

Journal of Molecular Catalysis A: Chemical

View full text Add to dashboard Cite

Proline-Based P, N Ligands in Asymmetric Allylation and the Heck Reaction

Cited by 66 publications

References 36 publications

The Application of HETPHOX Ligands to the Asymmetric Intermolecular Heck Reaction

The Application of HETPHOX Ligands to the Asymmetric Intermolecular Heck Reaction

The Development of Bidentate P,N Ligands for Asymmetric Catalysis

Novel bis(oxazoline) ligands derived from camphoric acid for Cu-catalyzed asymmetric cyclopropanation

Contact Info

Product

Resources

About