Copper(I)-catalyzed asymmetric 1,6-conjugate allylation

Abstract

Catalytic asymmetric conjugate allylation of unsaturated carbonyl compounds is usually difficult to achieve, as 1,2-addition proceeds dominantly and high asymmetric induction is a challenging task. Herein, we disclose a copper(I)-NHC complex catalyzed asymmetric 1,6-conjugate allylation of 2,2-dimethyl-6-alkenyl-4H-1,3-dioxin-4-ones. The phenolic hydroxyl group in NHC ligands is found to be pivotal to obtain the desired products. Both aryl group and alkyl group at δ-position are well tolerated with the corresponding products generated in moderate to high yields and high enantioselectivity. Moreover, both 2-substituted and 3-substituted allylboronates serve as acceptable allylation reagents. At last, the synthetic utility of the products is demonstrated in several transformations by means of the versatile terminal olefin and dioxinone groups.

Copper(I)‐Catalyzed Asymmetric Conjugate 1,6‐, 1,8‐, and 1,10‐Borylation

“…was performed. However,n oe nhanced enantioselectivity was observed but (R)-(S)-JOSIPHOS-5 led to the highest yields (entries [11][12][13][14][15]. Screening of the copper(I) source identified CuF(PPh 3 ) 3 •2MeOH as the best catalyst, as 3a was obtained in 85 %y ield with 91 % ee.…”

“…Here,b yu sing ap owerful copper(I)-JOSIPHOS catalyst, we develop asymmetric 1,6-, 1,8-, and 1,10-borylation of unsaturated dioxinones with excellent regio-and high enantioselectivities.P reviously,w ed isclosed ac opper(I)-NHC complex-catalyzed asymmetric 1,6-allylation of 2,2dimethyl-6-alkenyl-4H-1,3-dioxin-4-ones. [15] The2 ,2-dimethyl-4H-1,3-dioxin-4-one group was easily transformed to bketo-ester, a,b-unsaturated ester,a nd pyrazole in moderate yields,w hich demonstrated its synthetical versatility.…”

Catalytic Asymmetric Allylic Substitution with Copper(I) Homoenolates Generated from Cyclopropanols

“…( R , R )‐Ph‐PYBOX and ( S , S )‐ i Pr‐BOPA, two tridentate bisoxazoline ligands, were not beneficial for asymmetric induction either (entry 3, 81 % yield, 12 % ee ; entry 4, 87 % yield, 21 % ee ). Considering the powerful performance of Sawamura's NHC ligands in the copper(I)‐catalyzed asymmetric allylic substitution [3j,k, 4, 5g] and in the copper(I)‐catalyzed conjugate allylation, [12] we tried such ligands in the model reaction (NHC1‐4, NHC6, and NHC8 are known; NHC5, NHC7, and NHC9‐10 are new).…”

Copper-catalysed asymmetric reductive cross-coupling of prochiral alkenes

“…Recently, our laboratory and others reported copper-catalysed conjugative addition of alkylcopper 14 , 15 or allylcopper 16 , 17 nucleophiles to Michael acceptors using corresponding organoboron substrates or dienes, without using strongly basic and preformed nucleophiles such as Grignard and organolithium reagents. However, all those methods formed an alkyl-alkyl bond with a single stereocentre and especially, the addition of allyl copper species derived from dienes resulted in a mixture of (E) and (Z)-isomers 16 .…”