. Author manuscript; available in PMC: 2018 Jul 5.

Published in final edited form as: Tetrahedron Lett. 2017 May 25;58(27):2675–2680. doi: 10.1016/j.tetlet.2017.05.084

Table 2.

Survey of cyclization conditions for protected wollamide B linear precursor 10 to 11.

Entry	Cyclization conditions (equiv)	Conc. (M)	Reaction time (h)	Yield^a (%)
1	HBTU/DIPEA (1.02, 3)	0.001	0.5	72
2	HBTU/DIPEA (1.02, 3)	0.01	0.5	73
3	HBTU/DIPEA (1.02, 3)	0.05	0.5	71
4	HBTU/DIPEA (1.02, 3)	0.10	0.5	66
5	TBTU/DIPEA (1.02, 3)	0.001	0.5	61
6	DMTMM/DIPEA (3, 3)	0.001	0.5	59
7	PyBOP/DIPEA (1.5, 3)	0.001	0.5	68
8	EDC-HCl/HOBt/DIPEA (1.5, 1.5, 3)	0.001	54	43
9	DIC/HOBt/DIPEA (3, 3, 3)	0.001	1 week	30

Isolated yields after silica gel column chromatography.