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. Author manuscript; available in PMC: 2010 Jul 2.
Published in final edited form as: Tetrahedron. 2009 Jun 27;65(26):4957–4967. doi: 10.1016/j.tet.2009.03.103

Table 1.

NHC-catalyzed cyclization-lactonization of substrate 6.

graphic file with name nihms123358f13.jpg
entry Catalyst (mol%) Base (mol%) Solvent (conc.) Temp. (°C) A : B : Ca
1 IMesCl (20%) DBU(15%) THF (0.1M) 40 1 : – : 10
2 RMesCl (20%) DBU(15%) THF (0.1M) 40 1 : 1 : 2
3 IMesCl (20%) NEt3(15%) THF (0.1M) 40 2.5 : 2 : –
4 RMesCl (20%) NEt3(15%) THF (0.1M) 40 2.5 : 2.5 : 1
5 12(15%) DBU(10%) 10:1 THF:tBuOH (0.02 M) 40 1 : 1 : –
6 12(15%) DIPEA(100%) CH2Cl2 (0.1M) 40 1 : 1 : –
7 12(15%) DBU(10%) tBuOH (0.1M) 40 6.2 : 5.3 : 1
8 12(15%) DBU(10%) tBuOH (0.1M) 60 1.4 : 1 : –
9 12(15%) NEt3(10%) tBuOH (0.1M) 60 1.6 : 1 : –
10 12(15%) DBU(10%) tBuOH (0.1M) 80 1.4 : 1 : –

All reactions listed proceeded with 100% conversion; isolated yields were not determined.

a

Product pathway ratios determined from 1H NMR analysis of unpurified reaction mixtures.