Hall, R. H. et al. published their research in Chemistry & Industry (London, United Kingdom) in 1955 | CAS: 13417-49-7

5,6-Dihydro-2H-pyran-3-carbaldehyde (cas: 13417-49-7) belongs to tetrahydropyran derivatives. Dihydropyrans and tetrahydropyrans are examples of cyclic ethers widespread in nature. The reaction of tertiary 1,4- and 1,5-diols with cerium ammonium nitrate at room temperature gives tetrahydrofuran and tetrahydropyran derivatives in high yield and stereoselectivity. Various fragrant compounds have been synthesized using this method.Formula: C6H8O2

Derivatives of acraldehyde dimer was written by Hall, R. H.. And the article was included in Chemistry & Industry (London, United Kingdom) in 1955.Formula: C6H8O2 This article mentions the following:

Acid treatment of HOCH2CH2CHO (C.A. 44, 10725c) gave a final product formulated as 3-formyl-Δ3-dihydropyran 2,4-dinitrophenylhydrazone (I), m. 228° and the probable parent aldehyde (II) is described (C.A. 44, 8378a) but there is no proof of structure of I or II. Preparation of II [b12 77-8° nD20 1.4979; semicarbazone, m. 216-17° (cf. C.A. 44, 8378a)] and formation of the 2,4-dinitrophenylhydrazone, m. 234.5° (decomposition, pre-heated bath) showed that I was this derivative of II by mixed m.p. and ultraviolet spectra (λ in EtOH 376 mμ, E about 28,000). Reduction of II over Pt gave 45% 3-formyltetrahydropyran (III), b10.5 69-70°, nD20 1.4533; 2,4-dinitrophenylhydrazone, m. 154-5°. Ag2O-Ba(OH)2 oxidation of III yielded 90% of the acid, m. 97-8°; anilide, m. 131-2° (this and other derivatives were identical with authentic material). The ultraviolet spectrum showed α,β-unsaturation in II and the double bond was shown by nonidentity of the acid and derivative from II with authentic Δ2-derivative thus showing that I and II have a Δ3-structure. Complete reduction of II gave 3-hydroxymethyltetrahydropyran, b11 104°, nD20 1.4624; phenylurethan, m. 89°. Treatment of Δ3-dihydropyran-3-carboxylic acid with Raney Ni in aqueous alkali at 100° yielded only a trace of Δ2-acid and this on decarboxylation gave only a trace of Δ2-dihydropyran. In the experiment, the researchers used many compounds, for example, 5,6-Dihydro-2H-pyran-3-carbaldehyde (cas: 13417-49-7Formula: C6H8O2).

5,6-Dihydro-2H-pyran-3-carbaldehyde (cas: 13417-49-7) belongs to tetrahydropyran derivatives. Dihydropyrans and tetrahydropyrans are examples of cyclic ethers widespread in nature. The reaction of tertiary 1,4- and 1,5-diols with cerium ammonium nitrate at room temperature gives tetrahydrofuran and tetrahydropyran derivatives in high yield and stereoselectivity. Various fragrant compounds have been synthesized using this method.Formula: C6H8O2

Referemce:
Tetrahydropyran – Wikipedia,
Tetrahydropyran – an overview | ScienceDirect Topics