3,4-Dihydro-2H-Pyrandichloropropene: A Versatile Compound in Organic Synthesis？ ¹

What is the chemical name of 3,4-Dihydro-2H-Pyrandichloropropene?

What is the molecular formula of 3,4-Dihydro-2H-Pyrandichloropropene?

What is the molecular weight of 3,4-Dihydro-2H-Pyrandichloropropene?

What is the CA registration number of 3,4-Dihydro-2H-Pyrandichloropropene?

What are the physical properties of 3,4-Dihydro-2H-Pyrandichloropropene?

What precautions should be taken when handling 3,4-Dihydro-2H-Pyrandichloropropene?

How is 3,4-Dihydro-2H-Pyrandichloropropene used in organic synthesis?

One: Tetrahydropyranyl Protection of Alcohols

Tetrahydropyranyl (THP) protection of alcohols is a useful tool in organic synthesis. The reaction of chiral alcohols with 2,3-dihydropyran introduces another asymmetric center, resulting in a mixture of diastereomers. Although this poses challenges in purification and spectroscopic analysis, it does not hinder its successful application.

Under very mild reaction conditions (0 ℃, 1 h, 89%~100%), alcohols can undergo tetrahydropyranylation using (trimethylsilyl) sulfates, even with allylic alcohols without rearrangement reactions.

The decomposition of tetrahydropyran derivatives can be selectively cleaved by organotin phosphates in MEM ethers, MOM ethers, and 1,3-dioxolane conditions. The catalyst can be reused. In the presence of tert-butyldimethylsilyl, acetyl, methanesulfonyl, and methoxymethyl ethers, as well as in the presence of methanesulfonyl catalyst Me2Sn(SMe)2-BF3·Et2O, selective cleavage of primary, secondary, and tertiary alcohols occurs.

A simple and highly chemoselective method for tetrahydropyranylation of alcohols and phenols is carried out at room temperature using a catalytic amount of AlCl3 supported on polystyrene. This method exhibits high selectivity for the mono-protection of symmetrical diols.

Two: Tetrahydropyranyl Protection of Thiols

Tetrahydropyranyl derivatives of thiols can be used in masking reactions of functional groups.

Compared with O-tetrahydropyran ethers, S-tetrahydropyran ethers can also exist stably under conditions of 4mol/L HCl-MeOH. Deprotection reactions using silver nitrate or hydrogen bromide-trifluoroacetic acid are easily carried out with high yields. Oxidation reactions can occur with iodine, thiocyanate, and disulfides.

Three: Tetrahydropyranylation of Amines

In the presence of catalytic p-toluenesulfonic acid, purines react with 2,3-dihydropyran to generate 9-(2-tetrahydropyran) derivatives.

Four: Ring Opening Reactions of Dihydropyran

Treatment of dihydropyran with n-butylsodium or n-butyllithium generates trans-4-hydroxy-1-alcohols.

Five: Other Applications

Tetrahydropyranyl-protected groups have wide applications in organic synthesis. The use of Gilman cuprate reagents with chain-end protecting ethers can introduce the structure of cis-CH=CHCH2OH.

The pyridine compounds generated from the reaction of dihydropyran with BrCH2C(NOH)CO2Et can be used in the synthesis of amino triesters.

References

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3. Menger, F. M.; Chu, C. H. J. Org. Chem., 1981, 46, 5044.

4. Sato, T.; Otera, J.; Nozaki, H. J. Org. Chem., 1990, 55, 4770.

5. Speziale, A. J.; Ratts, K. W.; Marco, G. J. J. Org. Chem., 1961, 26, 4311.

6. Corey, E. J.;Wollenberg, R. H. J. Org. Chem., 1975, 40, 2265.

7. Gallos, J. K.; Sarli, V. C.; Massen, Z. S.; Varvogli, A. C.; Papadoyanni, C. Z.; Papaspyrou, S. D.; Argyropoulos, N. G. Tetrahedron, 2005, 61, 565.

8. Tamami, B.; Borujeny, K. P. Tetrahedron Lett., 2004, 45, 715.