Enantioselective, Desymmetrizing Bromolactonization of Alkynes

Wilking, Michael; Mück‐Lichtenfeld, Christian; Daniliuc, Constantin G.; Hennecke, Ulrich

doi:10.1021/ja402910d

Cited by 131 publications

(68 citation statements)

References 53 publications

(20 reference statements)

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“…[30] Diynes 1a-d, [19] 1e, [31] 1f, [19] 1g and 1h, [32] 1j, [19] 1k, [33] 1l, [19] 1m, [34] 1n, [19] 1o and 1p, [35] and 1q [36] were prepared as described in the literature.D iyne 1i wasp urchased. Cyanamides 2b, [37] and 2i [15] were prepareda sd escribedint he literature.Cyanamide 2a was purchased.…”

Section: Methodsmentioning

confidence: 99%

Iridium‐Catalyzed [2+2+2] Cycloaddition of α,ω‐Diynes with Cyanamides

et al. 2015

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Thec omplex[ Ir(cod)Cl] 2 /DPPF or rac-BINAP is an efficient catalyst for the [2+ +2+ +2] cycloaddition of a,w-diynesw ith cyanamides.Awide range of cyanamides derived from secondary amines are good coupling partners for a,w-diynes. Ther eaction of unsymmetrical a,w-diynes possessingt wo different internal alkyne moieties with cyanamides is regioselective.Ac ompetitive experiment showed that cyanamide is more reactive than nitrile. This higher reactivity of cyanamide than nitrile was analyzed based on density functional theory (DFT)c alculations at the B3LYP level.

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Section: Methodsmentioning

confidence: 99%

Iridium‐Catalyzed [2+2+2] Cycloaddition of α,ω‐Diynes with Cyanamides

et al. 2015

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“…31 Enantioenriched bromoenol lactones 72 containing a tetrasubstituted alkene and a quaternary center were prepared using dimeric chinchona alkaloid derivative 73 and NBS (Table 6). Internal alkynes generally yielded products with higher enantiopurity.…”

Section: Organocatalyticmentioning

confidence: 99%

Nonenzymatic enantioselective synthesis of all-carbon quaternary centers through desymmetrization

Petersen

2015

Tetrahedron Letters

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The asymmetric desymmetrization of meso or prochiral compounds containing an all-carbon quaternary center is an attractive alternative to classical synthetic approaches aimed at the asymmetric formation of a new C—C bond. This review focuses on nonenzymatic desymmetrizations that utilize transition metal catalysts or organocatalysts to distinguish between enantiotopic groups to generate enantioenriched compounds containing all-carbon quaternary stereocenters.

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“…Reactions with bromine sources, such as DBDMH and NBS produced complex mixtures, while NIS gave 3a in moderate yield (62%, entry 2) with an enantiomeric ratio (er) of 64:36 indicating a definite but low enantioselectivity. Changing the reaction media to toluene or CH 3 CN, and lowering the reaction temperature to −40°C did not improve the selectivity (entries [3][4][5]. The use of I(collidine) 2 PF 6 12 or ICl also did not give any improvements (entries 6 and 7).…”

Section: Figurementioning

confidence: 99%