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. Author manuscript; available in PMC: 2015 Sep 8.
Published in final edited form as: Chemistry. 2014 Jul 30;20(37):11726–11739. doi: 10.1002/chem.201402353

Table 8.

Optimization of allene formation from 2-B(pin)-substituted allylic acetate 1f.

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Entry [Pd] Ligand (mol %) Base (equiv) Time (h) Yield (%)[b]
recovered 1f 10a
1 Pd(PPh3)4 – – 1.5 80 0
2 Pd(PPh3)4[c] – – 1.5 0 4
3 Pd(PPh3)4 – Cs2CO3 (1) 1.5 0 87
4 – – Cs2CO3 (3) 1.5 95 <2
5 Pd(OAc)2 PPh3 (2) Cs2CO3 (1) 1.5 0 73
6 [Pd(allyl)Cl]2 PPh3 (2) Cs2CO3 (1) 1.5 0 80
7 [Pd(allyl)Cl]2 DPPE (2) Cs2CO3 (1) 1.5 12 72
8 [Pd(allyl)Cl]2 PCy3 (1.5) Cs2CO3 (1) 1.0 0 93
9 [Pd(allyl)Cl]2 CyJohnPhos (1.5) Cs2CO3 (1) 1.0 0 99
10 [Pd(allyl)Cl]2 CyJohnPhos (1.5) – 1.0 90 7
11 [Pd(allyl)Cl]2 CyJohnPhos (1.5) Cs2CO3 (0.5) 1.0 0 94
12 [Pd(allyl)Cl]2 CyJohnPhos (1.5) Cs2CO3 (3) 1.0 15 85
13 [Pd(allyl)Cl]2 CyJohnPhos (1.5) NaOAc·3H2O (3) 1.0 78 19
14 [Pd(allyl)Cl]2 CyJohnPhos (1.5) K2CO3 (3) 1.0 59 41
15 [Pd(allyl)Cl]2 CyJohnPhos (1.5) NaHCO3 (3) 1.0 0 76
16 [Pd(allyl)Cl]2 CyJohnPhos (1.5) NaHCO3 (1) 1.0 0 90
[a]

Reactions conducted at 0.17 M concentration on 0.04 mmol scale.

[b]

Yield determined by 1H NMR integration of the crude reaction mixture using 1,4-dimethoxybenzene as the internal standard.

[c]

1 equiv of Pd(PPh3)4.