Synthesis of New Type Diacetal Trioxa-Cage Compounds via an Intramolecular Nucleophilic Addition of the Hydroxy Group to the Carbonyl Oxide Group

Abstract

The synthesis of diacetal trioxa-cage compounds with a new type of skeleton is reported. Ozonolysis of the diols 2a − f, 21, 24, and 33 in CH2Cl2 at −78 °C followed by reduction with Me2S gave the diacetal trioxa-cages 3a − f, 22, 25, and 34 in 70−80% yields, respectively. A mechanism via an intramolecular nucleophilic addition of the hydroxy group of the diols to the carbonyl oxide group is proposed for the formation of the diacetal trioxa-cages. The effect of the number of carbon atoms at the bridge of the diols on the formation of the diacetal trioxa-cage skeleton was examined. Ozonolysis of the diols 13 and 15 under the same reaction conditions gave compounds 16 and 18, respectively. No detectable amount of the trioxa-cages 17 and 19 was obtained. For the synthesis of the diacetal trioxa-cages 28a − c and 31, which possess an alkene bond intact, ozonolysis of the diols 27a − c and 30 was performed by controlling the amount of ozone.

Catalytic Enantioselective Desymmetrization of Norbornenoquinones via C(sp2)–H Alkylation

“…However, the product ( 6 ) was obtained with poor diastereoselectivity (1.6:1 dr). Reduction of 3aa and 3la under Luche conditions was found to be completely regio- and diastereoselective and furnished the corresponding diols 7 and 8 , respectively, in high yields . The relative and absolute stereochemistry of 8 was established from its single crystal X-ray diffraction analysis .…”

Diels−Alder Cycloadditions of Ethyl 2-Carbomethoxyethenesulfinates with Cyclopentadiene. Lewis Acid Enhancement and Adduct Identification with the Assistance of Competitive Stereodifferentiating Iodolactonization and Iodosultinization Reactions

“…Indeed the cyclization demonstrates how a sulfur functionality can assist in the regiospecific oxidation of a remote double bond. Furthermore, use of the iodosultinization in a context similar to that presented here represents a new reaction for the construction of oxa- (and thia-) cage compounds …”

Anti-Addition Mechanism in the Intramolecular Hydroalkoxylation of Alkenes Catalyzed by PVP-Stabilized Nanogold

“…Also, we chose a α,α-diaryl tertiary alcohol like 1c according to our previous results [9]. The precursor of 1c (compound 6 ) was prepared by the Diels-Alder reaction of 1,4-naphthoquinone with cyclopentadiene according to the literature [30]. Phenyl Grignard reagent attacked one of the carbonyl groups selectively from the exo side to afford the endo tertially alcohol in 86% yield (Scheme 3).…”