Synthesis Of Heterocycles And 1,3-butadienes Based On Aldo-X Bifuctional Building Blocks

Aldo-X bifunctional reagents are a wide class of molecules that contain at least two reactive sites, among them one aldehyde, acetal or semiacetal group is involved. These reagents have been widely used in organic synthesis due to their diverse reaction activity. In this article, a variety of new reactions were developed, with which, furan, pyrrole, indole, carbazole et al can be obtained. The main work can be generally divided into four parts:1. Six unreported multi-component reactions were developed divergently by combining Aldo-X bifunctional building blocks, ketene dithioacetal and indole or aniline, with this methodology, several important heterocycles, such as dihydrochromene, dihydrocoumarin, furan and pyrrole were synthesized;2. Some 2-nuclophile substituted furan, pyrrole and dihydrothiophene derivatives were synthesized using masked aldo-X bifunctional building blocks-dihyrofuran as the "model" reagent. This novel reaction involves an electrophilic ring-opening, ring-closing and oxidation heteroaromatization tandem step;3. Masked aldo-X bifunctional building blocks-dihydrofuran was used as benzannulation reagent. Indole, carbazole, benzofuran, benzothiophene and naphthalene derivatives can be achieved with this benzannulation reaction protocol;4. Masked aldo-X bifunctional building blocks-dihydropyran was used as starting material to synthesize 1,3-butadiene derivatives. In this reaction, a novel dual metal synergetic catalytic system was developed by combining copper bromide and manganese chloride together. Based on this methodology,1,3-butadiene derivative was synthesized through reaction between common aliphatic aldehyde and ketene dithioacetal. What's more, this 1,3-butadienes can be converted into pyrrole, thiophene and naphthalenone under mild conditions.