Table 1.

Investigation of metal-mediated allylation conditions for the synthesis of the 5,7,5-fused guaianolide lactone system.

Entry	Conditions[a,b]	11	14	15	rsm
1	CrCl2, cat. NiCl2, DMF, 60 °C	10%[e]	17%	↕	↕
2	In0, NaI, DMF, 60 °C	13%[f]	↕	↕	↕
3[c]	NaI; SmI2, HMPA-THF, −78 °C	27%[e]	17%	↕	↕
4[c]	NaI; Zn0, aq. NH4Cl, THF, rt	0%	51%	↕	34%
5[c]	NaI; Mg0, cat. (CH2Br)2, THF, rt	0%	↕	↕	↕
6[c]	NaI; iPrMgCl, THF, 0 °C	0%	↕	↕	↕
7[c]	NaI; SnCl2, DMF, rt	53%[f]	↕	20%	9%
8[d]	SnCl2, NaI, DMF, 60 °C	90%[f]	↕	↕	↕

^[a]Reaction performed on a 30-mg scale unless otherwise stated;

^[b]Isolated yields are reported;

^[c]Starting material first reacted with NaI in acetone for 8 h;

^[d]Reaction performed on a 7-gram scale;

^[e]Diastereomeric ratio 2:1 11:8-epi-11;

^[f]Single diastereomer obtained.