Marschall, Helga et al. published their research in Liebigs Annalen der Chemie in 1982 | CAS: 13417-49-7

5,6-Dihydro-2H-pyran-3-carbaldehyde (cas: 13417-49-7) belongs to tetrahydropyran derivatives. In organic synthesis, the 2-tetrahydropyranyl group is used as a protecting group for alcohols. 2-(Arylmethylene)cyclopropylcarbinols could be converted to the corresponding tetrahydropyrans stereoselectively in the presence of Brønsted acids under mild conditions. A plausible Prins-type reaction mechanism has been proposed.Reference of 13417-49-7

Synthesis of hydroxy-γ-lactones from α,β-unsaturated aldehydes was written by Marschall, Helga;Penninger, Josef;Weyerstahl, Peter. And the article was included in Liebigs Annalen der Chemie in 1982.Reference of 13417-49-7 This article mentions the following:

RCH:CR1CHO [I; R = Me, R1 = H; RR1 = (CH2)3-5, CH2CH2OCH2, CH2CH2CH2CMe2], Me2C:CHCHO (II), and III (R3 = CHO, R4R5 = bond) reacted in three steps (epoxidation, PO olefination, and selective hydrogenation to give the corresponding esters IV (R2 = CH2CH2CO2Et), IV (R = CH2CH2CO2Et, R1 = R2 = Me) and III (R3 = CH2CH2CO2Et, R4R5 = O). These steps were interchangeable, especially the epoxidation and olefination. These esters were hydrolyzed to give V [R6 = H, R7 = R8 = Me; R6R7 = (CH2)n, CH2OCH2CH2, R8 = H; R6R7 = CMe2CH2CH2CH2, R8 = Me; n = 4-5]. In the experiment, the researchers used many compounds, for example, 5,6-Dihydro-2H-pyran-3-carbaldehyde (cas: 13417-49-7Reference of 13417-49-7).

5,6-Dihydro-2H-pyran-3-carbaldehyde (cas: 13417-49-7) belongs to tetrahydropyran derivatives. In organic synthesis, the 2-tetrahydropyranyl group is used as a protecting group for alcohols. 2-(Arylmethylene)cyclopropylcarbinols could be converted to the corresponding tetrahydropyrans stereoselectively in the presence of Brønsted acids under mild conditions. A plausible Prins-type reaction mechanism has been proposed.Reference of 13417-49-7

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