The Nitro Ketal Approach to Furane Systems. Total Synthesis of Racehic Bilobanone

Continuing our studies with the chemistry of ketals of β-nitro ketones¹, we wish to describe a new furane synthesis exemplified by a total synthesis of the sesquiterpene bilobanone 1 ².     

The Reaction of (Phenyldimethylsilyl)dichloromethyllithium with Organoboranes. A Synthesis of α-Hydroxyorganosilanes and Ketones

The α-transfer reaction of organoboranes has been utilized to great advantage in the employment of organoboranes in synthesis.² We report here that this process can be used as illustrated in eq 1 to generate α-hydroxyorganosilanes, which can be converted to ketones. This procedure serves to incorporate two of the groups of the organoborane into the product as well as generating the hydroxyl group via oxidation of the newly formed carbon-boron bond.     

A Rapid and Efficient Method for Dehydration of Primary Amides to Nitriles. Preparation of Acrylonitrile Derivatives

Chloromethylene iminium salts (Vilsmeier reagents) have a long history and thoroughly investigated chemistry⁽¹⁾. Chloro-N, N-dimethylforminium chloride 1 is most conveniently generated by the reaction of N, N-dimethylformamide (DMF) with oxalyl chloride⁽²⁾. The reagent has also been obtained usingthicnyl chloride at elevated temperature and a variety of acid chlorides^(1b). The literature describes several examples of the use of thionyl chloride in combination with DMF in which 1 or a related species is thought to function as the reactive intermediate in the transformation of amides to nitriles⁽³⁾.     

Regioselective Intramolecular Carbon-Hydrogen Insertion in Copper-Catalyzed Carbenoid Decompositions of cis-1-Methyl-3-Arylcyclohexane-1-Diazomethyl Ketones : Some Synthetic Applications

Recently, we have developed¹ a new route for the stereo-specific introduction of an angular carboxyl or functionalized methyl groups² in a rigid hydrophenanthrene moiety. The key step in this approach is a regioselective intramolecular α-keto carbenoid insertion across the benzylic C-H bond (at C-4a) in CuSO₄-catalyzed thermal decomposition of the diazoketones and to the corresponding tetracyclic ketones and in moderate to good yields. A modified procedure³ of carbenoid decomposition of these diazoketones, in the presence of Cu₂O under irradiation with tungsten filament lamp, improves the yields of the desired C-H insertion products. Thus, the ketones and have been prepared now in consistently higher yields (53-55%) from the pure diazoketones , m.p. 125-127°, and , m.p.     

Alumina-Assisted Basic Hydrolysis of Esters1

“Anhydrous hydroxide” formed by reaction of 2 equiv of potassium tert-butoxide with 1 equiv of water in dry ether serves as a useful reagent for hydrolyzing esters and tertiary amides at ambient temperatures.² During the course of our studies dealing with alumina as a support and as a catalyst for solid-liquid biphase reactions, we have discovered that potassium hydroxide crushed together with neutral alumina (reagent 1) provides the basis for an equally effective means for carrying out ester hydrolysis.^3,4 Moreover, isolation of the alcohol is readily accomplished by simple filtration and solvent evaporation.