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. Author manuscript; available in PMC: 2013 Nov 12.
Published in final edited form as: Angew Chem Int Ed Engl. 2012 Oct 12;51(46):11491–11495. doi: 10.1002/anie.201206904

Table 1.

Key ring closure of 5 via an umpolung allylation.

graphic file with name nihms-455742-t0005.jpg

# catalyst ligand reduct. solv. base 1[a]
1 Pd(PPh3)4[b] -- Et2Zn[c] THF -- 19
2 Pd(PPh3)4[b] -- Et2Zn THF -- 10-30
3 PdCl2(PPh3)2 -- Et2Zn THF K2CO3 13-42
4 PdCl2(PPh3)2 -- Et2Zn DMF K2CO3 32
5 PdCl2(PPh3)2 -- Et2Zn DMA K2CO3 42 [d]
6 PdCl2(PPh3)2 -- Et2Zn DMA -- 33
7 PdCl2(PPh3)2 -- Me2Zn DMA K2CO3 0
8 PdCl2(PPh3)2 -- Bu2Zn DMA K2CO3 31
9 Pd(OAc)2 PPh3 Et2Zn DMA K2CO3 15

Standard conditions unless otherwise stated: cat. (10 mol %), ligand (20 mol %), K2CO3 (1.5 equiv), solvent (0.033 M overall), 5 (100–600 mg scale, 1.0 equiv., 0.05 M, slow addition over 1.5 h), reductant (1.5 equiv., slow addition over 1.5 h), T = 50 °C.

[a]

Isolated yield.

[b]

Cat. (20 mol %).

[c]

4 Equiv of Et2Zn.

[d]

Reproduced on six occasions, 42% was obtained for gram-scale.

THF = tetrahydrofuran, DMF = N,N,dimethylformamide, DMA = N,N-dimethylacetamide.