10.1021/jo001737+
The research focuses on the synthesis of (-)-delobanone, a sesquiterpene, using a novel approach that involves the preparation of alkenyl cyclopropane 2 from the Sharpless-derived epoxide 1. The key reactants include geraniol, which undergoes Sharpless epoxidation to form an epoxide, followed by sulfonylation to produce benzenesulfonate 11. This is then reacted with lithioacetonitrile to yield nitrile 9, which is further transformed into aldehyde 8 through a DIBAL-H reduction. The aldehyde is converted into an alkenyl cyclopropane 2 via a Wittig reaction. The final step involves the irradiation of 2 in the presence of Fe(CO)5 under a CO atmosphere to achieve the ring expansion, resulting in (-)-delobanone 3. Throughout the synthesis, various analytical techniques were employed, including NMR, IR, MS, and optical rotation measurements, to monitor the progress and confirm the structures of the intermediates and final product. The research also discusses the potential challenges and the successful optimization of the reaction conditions to achieve high yields and selectivity.
10.1002/hlca.200890211
The present study aimed to develop a practical and highly regio- and stereoselective method for the synthesis of oligoisoprenols, essential precursors for the synthesis of biologically important isoprenoids. The convergent synthetic strategy described is characterized by iterative allyl-allyl couplings of monomers derived from commercially available geraniol and repeated reductive elimination of p-toluenesulfonyl (Ts) groups. The study successfully demonstrated the use of this approach to synthesize (all-trans)-oligoisoprenols, such as (all-trans)-octaprenol and (all-trans)-decaprenol, which is more efficient and practical compared to previous methods. The key chemicals used in the process include geraniol, p-toluenesulfonyl, allyl bromide, allyl sulfone, and various reducing agents such as Li/EtNH2, Na/EtOH, Na/naphthalene, and LiHBEt3/Pd(dppp)Cl2. The study concluded that the developed convergent strategy is an effective method for the synthesis of long linear polyprene backbones.
10.1006/jcat.1999.2803
The research investigates the liquid-phase hydrogenation of citral over Pt/SiO2 catalysts, aiming to understand the effects of temperature on the reaction's activity and selectivity. Citral, an a,?-unsaturated aldehyde with a conjugated C==C-C==O bond system and an isolated C==C bond, is hydrogenated to produce various products like unsaturated alcohols (UALC), partially saturated aldehydes (PSALD), and completely saturated alcohols (SAT). The study finds that the reaction rate exhibits an unusual activity minimum at 373 K, attributed to the interplay between the decomposition of unsaturated alcohols (geraniol and nerol) and the desorption of CO. At lower temperatures (298 K), the reaction rate decreases significantly due to CO accumulation blocking active sites, while at higher temperatures (373 K and above), the enhanced CO desorption rate allows for stable activity and conventional Arrhenius behavior. The researchers propose a kinetic model based on Langmuir–Hinshelwood kinetics, incorporating dissociative adsorption of hydrogen, competitive adsorption between hydrogen and organic compounds, and the addition of a second hydrogen atom as the rate-determining step. The model successfully describes the observed product distributions and the unusual temperature dependence of the reaction rate.
Xi
Xi:Irritant;
