Table 3.

Grignard reagents with β‐hydrogen atoms.

Entry	Carboxylate	Grignard reagent	Allene	Yield [%]
1				93
2				68
3				64
4				75
5				78
6		CyMgCl		71
7				63
8				90
9				70
10				61
11				61
12				31[b] (24)[c] 44[b] (34)[c]
13				39
14				25(Bz) 24(Piv) 14(Ac)

[a] Yield of product isolated from the reaction run with a 0.2 m solution of propargyl carboxylate (1–2 mmol) in Et₂O, with dropwise addition of the Grignard reagent during 5 min. [b] From 0.25 mmol of substrate (R=Piv). [c] From 0.5 mmol of substrate (R=Ac).