Direction of Ring Opening of Styrene Oxide and Butadiene Monoxide by Ester Carbanions†

Abstract

Attack takes place at both primary and secondary epoxy carbons of styrene oxide and butadiene monoxide on reaction with ester carbanions, providing evidence for the conjugative effect in these systems.

References

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14. 10i: 2.4 (2 H, m, H²); 2.4–1.9 (2 H, m, H³); 4.82 (1 H, m, H⁴); 5.1–5.5 (2 H, m, vinyl CH₂); 5.7–6.1 (1 H, m, vinyl CH). 11i: 2.4 (2 H, m, H²); 3.2 (1 H, sextuplet, H³); 3.92–4.36 (2 H, dq, H⁴); 5.1–5.3 (2 H, m, vinyl CH₂); 5.6–6.1 (1 H, dq, vinyl CH).
15. 8e: 7.3 (5 H, C₆H₅): 5.85 (0.22 H, PhCH–O); 5.6 (0.55 H); 4.35 (0.9 H); 2.2–3.2 (2, 5 H). 9e: 7.3 (5 H, C₆H₅); 4–5 (3 H, m).
16. R. M. Adams and C. A. VanderWerf, J. Am. Chem. Soc., 1950, 72, 4368.
17. 8e: mp 131.4–132.5 °C (113–115,¹¹ diastereoisomers 93–94 and 133–134 °C¹³). 9e: mp 93.4–94.0 °C (93–95,¹² 126–128 °C¹¹). 10h: mp (45–46,¹¹ 37–38,⁸ 36–37 °C⁹). 11h: mp (37–38,¹¹ 45–46,⁸ 49–50,¹² 47–48 °C⁹).
18. 8f: 5.6–6.0 (CH=CH₂); 5.2–5.5 (CH=CH₂); 4.8–5.0 (CH–O); 3.5–4.0 (CHCN); 2.0–3.0 (CH₂). 9f: 5.0–6.0 (CH1=CH₂); 3.5–4.5 (CHCN and CH₂–;O); 3.0–4.0 (CHCH₂).
19. 12: 5.5–6.0 (dd, J^{3α–4,3β–4}, 5.4, 10.9 PhCH); 4.2–4.6 (dd, J^{3α–2,3β–2}, 8.3, 12.0, CNCH, D₂O exchangeable); 3.1–3.5 (m, H^3α); 2.5–3.0 (m, H^3β). 13: 5.8–6.0 (dd, J^{3α–4,3β–4}, 8.0, 7.0, PhCH); 4.2–4.4 (dd, J^{3α–2,3β–2}, 9.0, 10.0, CNCH). Assignments confirmed by decoupling experiments.