. Author manuscript; available in PMC: 2008 Dec 5.

Published in final edited form as: J Am Chem Soc. 2006 Jul 12;128(27):8702–8703. doi: 10.1021/ja0609046

Table 1.

Optimization of deprotection and cyclization

entry	i. deprotection	ii. cyclization	time	yield^a
1	TFA, CH₂Cl₂	standard work-up^b	--	30
2	TFA, CH₂Cl₂	THF or CH₂Cl₂, K₂CO₃	20h	0
3	TFA, CH₂Cl₂	CH₂Cl₂, H₂O, K₂CO₃	5h	38
4	4N HCl /dioxane	THF or CH₂Cl₂, K₂CO₃	20h	0
5	4N HCl /dioxane	CH₂Cl₂, H₂O, K₂CO₃	1h	74
6	4N HCl /dioxane	THF, H₂O, K₂CO₃	1h	75
7	4N HCl/dioxane	MeOH, K₂CO₃	15 min	87
8	TMS-I, CH₂Cl₂	MeOH, K₂CO₃	30 min	95

Isolated yield.

CH₂Cl₂/sat. aqueous NaHCO₃ (1:1).