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. Author manuscript; available in PMC: 2012 Nov 2.
Published in final edited form as: J Am Chem Soc. 2011 Oct 11;133(43):17494–17503. doi: 10.1021/ja207727h

Table 1.

Cyclization Reactions to Form 22

graphic file with name nihms331049t1.jpg
Entry R Conditions Yield
22a
1 OH (35) DEAD, PPh3, CH2Cl2 0%
2 OH (35) 0.2 equiv CSA, CHCl3, rt, 12 h 54%
3 OMe (37) 1.2 equiv BF3• OEt2, CH2Cl2, 0 °C, 1 h 66%
4 F (39) 2 equiv SnCl2, DMF, rt, 18 h 71%
a

Yield reported as conversion from methyl ester precursor (34, 36, and 38, respectively)