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. Author manuscript; available in PMC: 2021 Jan 20.
Published in final edited form as: Angew Chem Int Ed Engl. 2019 Dec 12;59(4):1532–1536. doi: 10.1002/anie.201913150

Table 1.

Synthesis of tetracycle 29: Selected optimization.

graphic file with name nihms-1058981-t0004.jpg
Entry[a] Activator Nucleophile Yield (29: 17-epi-29)[b]
1 BF3•OEt2 MgBr(C4H7) 36% (3:1)
2 BF3•OEt2 ZnBr(C4H7) 11% (2:1)
3 BF3•OEt2 CeCl2(C4H7) 10% (1:1.5)
4 TMSBr CuTC(CN)(C4H7) 17% (1:1)
5 BF3•OEt2 InCl2(C4H7) <5%
6 BF3•OEt2 In(C4H7)3 54% (1:1)
7 BF3•OEt2 In(C4H7)4•MgBr 64% (>20:1)
[a]

yields and selectivities determined by 1H NMR analysis.

[b]

yields based on amount of correct C15 diastereomer in starting 28.