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. 2015 Jan 15;20(1):1475-94.
doi: 10.3390/molecules20011475.

Seven-membered rings through metal-free rearrangement mediated by hypervalent iodine

Siguara Bastos Lemos Silva  1 , Adriana Della Torre  2 , João Ernesto de Carvalho  3 , Ana Lúcia Tasca Gois Ruiz  4 , Luiz F Silva  5
Affiliations

Seven-membered rings through metal-free rearrangement mediated by hypervalent iodine

Siguara Bastos Lemos Silva et al. Molecules. .

Abstract

A versatile and metal-free approach for the synthesis of carbocycles and of heterocycles bearing seven- and eight-membered rings is described. The strategy is based on ring expansion of 1-vinylcycloalkanols (or the corresponding silyl or methyl ether) mediated by the hypervalent iodine reagent HTIB (PhI(OH)OTs). Reaction conditions can be easily adjusted to give ring expansion products bearing different functional groups. A route to medium-ring lactones was also developed.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Compounds bearing seven-membered ring fused to aromatic ring.
Scheme 1
Scheme 1
Preparation of the unsaturated TMS ether 3a. HMDS: hexamethyldisilazane and TMSCl: trimethylsilylchloride.
Figure 2
Figure 2
Structure of substrates 3b–l and 4a.
Scheme 2
Scheme 2
Mechanism of the Ring Expansion of 2a. HTIB: [Hydroxy(tosyloxy)iodo]benzene.
Scheme 3
Scheme 3
Preparation of the Medium-Ring Keto-Lactone 11a.
Scheme 4
Scheme 4
Tandem Expansion/Addition of 2a and 4a by HTIB. HTIB: [Hydroxy(tosyloxy)iodo]benzene.
Scheme 5
Scheme 5
Mechanism for the Formation of 12f.
Figure 3
Figure 3
Structure of 17.
Scheme 6
Scheme 6
Mechanism for the Formation of 8ha.
Scheme 7
Scheme 7
Mechanism for the Formation of 20i.
See this image and copyright information in PMC

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