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Wang et al. Chem Synth 2023;3:9 https://dx.doi.org/10.20517/cs.2022.44 Page 5 of 9

26 e C5 CH Cl (0.1 mL) 40 °C 96 76 89
2
2
f
27 C5 CH Cl (0.1 mL) 35 °C 96 95 89
2
2
a
Unless noted, a mixture of 1a (0.05 mmol), 2a (0.06 mmol), and C (10 mol%) in the solvent (0.5 mL) was stirred at room temperature (rt) for
f
1
c
b
e
d
the time given. All dr > 20:1, determined by H NMR; isolated yield; determined by chiral-HPLC analysis; 2a (0.075 mmol); 2a (0.10 mmol); 1a
(0.10 mmol); 2a (0.20 mmol).

Scheme 3. Substrate scope of the reaction between benzoxazines 1 and N-tosyl-2-methylenebut-3-enoates 2. A mixture of 1 (0.1
1
mmol), 2 (0.2 mmol), and C5 (10 mol%) in CH Cl (0.1 mL) was stirred at 35 °C for 96 h. All dr > 20:1, determined by H NMR.
2
2
Products 3 were obtained in isolated yield. The enantiomeric excess (ee) was determined by chiral-HPLC analysis.
furnished the desired product 3ba in 78% yield with 86% ee and > 20:1 dr. Various substituents (R ), either
2
electron-withdrawing (F, Cl, Br) or electron-donating group (Me), could be introduced into the aromatic
ring of 2-(4H-benzo[d][1,3]oxazin-4-yl)acrylates with a slight effect on the reaction, affording the
corresponding products 3ca-fa in 73%-97% yields with 82%-92% ee and > 20:1 dr. A series of product 3ga-ja
with different acyl (R ) were also obtained in 82%-94% yield with 84%-89% ee and > 20:1 dr. No significant
3
electronic effect on the aromatic moiety was observed. With these encouraging data in hand, we turned our
attention to the scope of methyl 2-[aryl(tosylimino)methyl]acrylates 2. It was found that the aromatic ring
4
functionality (R ) of 2-[aryl(tosylimino)methyl]acrylates had a large influence on the yield, and the
corresponding products 3ab-ad were obtained in 48%-75% yields with 88%-93% ee and > 20:1 dr. The
hetero-aromatic 2-[aryl(tosylimino)methyl]acrylate 2e was also compatible to afford the desired product 3ae
in 47% yield with 87% ee and > 20:1 dr. Notably, the formation of side products led to a relatively low yield
of the desired product. Pleasingly, it was confirmed by these results that the C5-mediated asymmetric