Total synthesis of stevastelin B3

The total synthesis of stevastelin B3 was achieved using, as a key step, a method developed by us for the synthesis of 2-methyl-1,3-diols by Ti(III)-mediated diastereo- and regioselective opening of trisubstituted 2,3-epoxy alcohols, to carry out the stereoselective construction of its propionate-derived fatty acid segment.     

Synthesis of (3R,4S,5S,9S)-3,5,9-trihydroxy-4-methylundecanoic acid δ-lactone

Radical-mediated opening of a chiral trisubstituted epoxy alcohol using cp₂TiCl furnished the ‘2-methyl-1,3-diol’ moiety with the desired stereochemistry, which led to a total synthesis of (3R,4S,5S,9S)-3,5,9-trihydroxy-4-methylundecanoic acid δ-lactone 1.     

Efficient synthesis of polyfunctionalised enantiopure diazepanone scaffolds

The synthesis of polyfunctionalised enantiopure 1,4-diazepan-3-one scaffolds from l-serine derivatives and azidoepoxides readily available from either l-ascorbic or d-isoascorbic acid, allowing access to various configurations at chiral centres, is described. The key steps are the nucleophilic opening of the epoxide by the amine of serine followed by a lactonisation-lactamisation sequence.     

Large-scale synthesis of SB-462795, a cathepsin K inhibitor: the RCM-based approaches

Two stereoselective syntheses of SB-462795, a highly potent cathepsin K inhibitor, are described. Both routes feature a C5-C6 disconnection by ring closing metathesis to construct an azepane ring and are amenable to large-scale manufacturing.     

CH2和CH3分子在金属团簇Cun(n=1～6)上吸附性质

以σ-羟基环氧化合物作为模型化合物, 利用密度泛函中B3LYP/6-31G(d,p)的方法研究了三乙基铝促进的环氧化合物的重排还原有机串联反应机理. 根据乙烯消去和六元环重排顺序的不同可有两条可能的反应路径,路径I首先进行的是六元环的收缩重排,而且该步即决速步,能垒为116.62 kJ/mol;路径II中首先发生乙烯的消去然后进行六元环开环重排,开环反应步是该反应路径的决速步,相应的能垒为251.38 kJ/mol,如此高的能垒导致后续反应难于进行. 因此,路径I是更有利的反应路径,与实验结果一致.     

Synthesis of polyglycolic acid copolymers from cationic copolymerization of C1 feedstocks and long chain epoxides

Polyglycolic acid (PGA), which is an important biodegradable polymer, can traditionally be synthesized through the ring opening polymerization of glycolide (with mostly using tin octanoate catalyst). Our previous studies revealed that PGA was alternatively synthesized with one-step cationic polymerization of formaldehyde from trioxane and carbonmonoxide (CO), sustainable C1 feedstocks obtainable from biomethanol or biogas. PGA and its copolymers can be mainly used for the biomedical applications due to their biocompatibility and biodegradability. In order to utilize PGA in other marketing materials such as packaging, PGA should be specifically engineered to improve its physical properties by a copolymerization strategy utilizing appropriate comonomers since PGA displays brown or beige color and is not soluble in most organic solvents due to its very high crystallinity. In this study; to improve on the physical properties of PGA, such as melting temperature and solubility, polymerizations of trioxane, CO and a minor amount of epoxides with long side chains were performed under the same reaction condition as PGA homopolymer synthesis (DCM solvent, at 800 psi, with triflic acid catalyst, reaction time of 72 h). The results have shown that optimum polymerizations were achieved at lower reaction temperatures than that of PGA homopolymer synthesis (110 °C versus 170 °C). The melting temperatures of all copolymers are lower, and the colors of the copolymers have become lighter than that of PGA homopolymer. The solubilities of obtained copolymers also increased by increasing side chain length of epoxides in the polymer backbone.     

Approaches to installing a N-gem-dimethylmethylene-2-oxazolyl group and application to the synthesis of a second generation HIV protease inhibitor

Two syntheses of the title compound 1 were developed based on different approaches for installing the oxazole ring moiety. Formation and dehydration of ketoamide was initially used and scaled up to afford 1 on several kilogram scale, then oxazolyl anion/iminium coupling reaction was developed for a more convergent approach.