1,6-Dioxaspiro [4.4] nonanes from γ-(2-Furyl)-alkanols

Towards understanding the hydrodeoxygenation pathways of furfural–acetone aldol condensation products over supported Pt catalysts

“…On the other hand, the continuous increase in the yield of E can be explained by its higher stability, caused by the limitation of the ring-opening steps of the saturated ring. 33 Among the mentioned side reactions, the formation of 2-methyl-1,6-dioxaspiroij4,4]nonane (F) took place, likely through the intramolecular addition of the hydroxyl group on the double bond of D. 34 The extent of oxygen removal steps was confirmed by the formation of compounds such as 2-butyl-furan (H), 2-butyldihydrofuran (I), 2-propyl-tetrahydropyran (J) and 2-butyltetrahydrofuran (K). The deoxygenation steps took place mostly through dehydration or hydrogenolysis reactions which usually imply the interaction of Brønsted acid sites with the hydroxyl group.…”

“…The fast hydrogenation of this bond is enhanced by its favourable thermodynamic conditions, and also due to the absence of steric limitations, unlike the case of the furanic ring bonds. 19 34 In addition, D may undergo hydrogenation of the remaining double bond in the furanic ring, thus yielding E, or dehydration reactions forming 2-butyl-dihydrofuran (I). A similar step may occur directly from C, yielding 2-butyl-furan (H), which can be further hydrogenated to I. Alternatively, the furan C-O bond present in C may be hydrogenolysed resulting in the opening of the furanic ring.…”

Tailor-made biofuel 2-butyltetrahydrofuran from the continuous flow hydrogenation and deoxygenation of furfuralacetone

“…The formation of SP from FA has been reported before. 33 It is formed via the partially hydrogenated intermediate 4-(4,5dihydrofuran-2-yl)butan-2-ol (DHFA) which was not observed because of its high reactivity. The formation of OD requires an opening of the five-membered ring and takes place most likely while the aromatic ring is still intact, since the saturated ring is known to be more stable towards hydrogenolysis.…”

(5R*, 9S*)‐ and (5R*, 9R*)‐2,2,9‐Trimethyl‐1,6‐dioxaspiro[4.4]non‐3‐ene and their Dihydro Derivatives as New Constituents of Geranium Oil

“…Hydrogenation of l a and l b finally led to the dihydro derivatives 2a and 2b, resp. An independent synthesis for 2a/2b was effected based on the knowledge that /3-(2-fury1)alkanols cyclize to 1,6-dioxaspir0[4.4]nonanes on hydrogenation [29] [30]. For this purpose, rose furan (3) was epoxidized to 4.…”