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Please login or sign up for a free trial to access the full content. Reduction of Diols by Metal-Free Catalysis

DOI: 10.1055/sos-SD-226-00133

Tin, S.; de Vries, J. G.Science of Synthesis: Catalytic Reduction in Organic Synthesis, (20171233.

Although the deoxydehydration of vicinal diols often requires a transition-metal catalyst,[‌33‌,‌34‌] there are examples of methods where the latter is not required. One such practical method involves the use of formic acid as both the source of hydrogen and the catalyst for the reduction of vicinal diol groups.[‌35‌] Some examples with good to high yields of products 8 are shown in Table 1. Notably, the side products of this reaction are water and carbon dioxide (see Scheme 8 for the proposed mechanism). For cases in which the substrate contains additional hydroxy groups (e.g., glycerol, entries 1 and 2), the formation of allyl formate is also observed, but it can easily be separated from the product (see below for details). The conversion of glycerol into prop-2-en-1-ol can even be performed on a 500-gram scale (5.4 mol of starting material); 265 grams (84% yield) of the desired product was obtained. This proves that the method is scalable. It has also been shown that the configuration of the newly formed double bond depends on the relative stereochemistry of the hydroxy groups in the starting material. In the deoxydehydration of decane-3,4-diol, either the E- or Z-product is obtained selectively, depending on the stereochemistry of the starting material (entries 9 and 10). This suggests that exclusively syn-elimination of the hydroxy groups occurs.

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