An Alternative Route for Synthesis of Chiral 4-Substituted 1-Arenesulfonyl-2-imidazolidinones: Unusual Utility of (4S,5S)- and (4R,5R)-4,5-Dimethoxy-2-imidazolidinones and X-Ray Crystallography

Table 1

The BF₃-promoted region/stereoselective demethoxylation of DMIm with organocuprates^a.

Entry	R^1b	R^2M	Yield % (A.C.)^c
1	Ac	𝑡-BuLi	0
2	Mac		76 (R)
3	Ac	1-AdamantylMgBr	0
4	Mac		81 (S)

aThe reaction was performed by using Grignard reagent (4.0 eq), CuCN (4.4 eq), and BF₃⋅OEt₂ (2.0 eq) in the presence of LiCl (8.8 eq) at 0°C, for 3 h, unless otherwise stated.
^b(4𝑅, 5𝑅)-enentiomer was used with 𝑡-BuLi, while (4𝑆, 5𝑆)-enentiomer was used with 1-adamantylMgBr.
^cAbsolute configuration.