A short and efficient synthesis of (+)-disparlure and its enantiomer

A short and highly efficient approach was applied for the total synthesis of the gypsy moth sex pheromone (+)-disparlure and its enantiomer from isopropylidene D- and L-erythrose, using a common strategy.     

A fully stereocontrolled total synthesis of (+)-leucascandrolide A

A highly stereocontrolled total synthesis of leucascandrolide A, a cytotoxic 18-membered macrolide from the calcareous sponge Leucascandra caveolata, starts out with a Jacobsen asymmetric hetero Diels-Alder reaction to configure the 2,6-cis-tetrahydropyran ring. All the remaining oxygenated stereocentres are introduced with high selectivity by relying on substrate-based control. An efficient endgame depends on two Mitsunobu reactions, the first to close the macrolactone with inversion at C17 and the second to attach the oxazole-containing side chain at C5, followed by Lindlar hydrogenation of the two alkynes to provide (+)-leucascandrolide A.     

Palladium(II)-catalyzed intramolecular aminoacetoxylation of sugar derived alkenyl tosylsulfonamide: Total synthesis of l-deoxyallonojirimycin

Palladium catalyzed intramolecular aminoacetoxylation of d-ribose derived alkenyl tosylsulfonamide to deliver l-deoxyallonojirimycin in an overall yield of 19%. The preliminary screening of l-deoxyallonojirimycin against carbohydrate processing enzymes showed moderate inhibitory activity against α-glucosidase (yeast) and α-mannosidases.     

Total synthesis of (+)-crocacin A

Total synthesis of the potent antifungal and cytotoxic agent (+)-crocacin A is described. The crucial (Z)-5,6-enoic amide moiety in this molecule was built by stereoselective partial reduction of a skipped diyne precursor. The diene, thus obtained, was transformed into a silyl epoxide that was regioselectively opened with an azide ion to furnish an α-azido-β-hydroxyalkylsilane intermediate. Peterson elimination of this β-hydroxysilane component in the final step resulted in the formation of the (Z)-8,9-enamide moiety of the molecule leading to a successful completion of its total synthesis.     

雌舞毒蛾引诱剂: (＋)-(7R,8S)-7,8-环氧-2-甲基十八烷的不对称全合成

由雌舞毒蛾释放的性引诱剂由于在害虫防治方面的需求不断增加, 已有许多文献对其合成方法进行报道. 以正十一醛和环戊酮为起始原料, 用L-脯氨酸催化的不对称羟醛缩合反应构筑手性中心, 后经拜耶-维利格氧化, 维梯希烯化等步骤, 为雌舞毒蛾性引诱剂(＋)-(7R,8S)-7,8-环氧-2-甲基十八烷提供了一条简便高效的不对称合成新途径, 总收率为37.8%.     

The stereoselective total synthesis of (+)-garvensintriol

A simple and highly efficient stereoselective total synthesis of (+)-garvensintriol, isolated from the stem bark of Goniothalamus arvensis, is described using Sharpless kinetic resolution, MacMillan α-hydroxylation, and Horner-Wadsworth-Emmons olefination as the key steps.     

Enantioselective total synthesis of (+)-sarcandralactone A

An enantioselective total synthesis of the lindenane sesquiterpene (+)-sarcandralactone A has been accomplished for the first time. The synthesis features a SeO₂-mediated [2,3]-sigmatropic rearrangement for the facile construction of the tertiary allylic alcohol as a single diastereoisomer.     

Enantioselective total synthesis of (+)-3,4-epoxycembrene-A

A concise and efficient total synthesis of (+)-3,4-epoxycembrene-A 1, an epoxy cembrane diterpenoid from tropical marine soft coral, is described. The synthesis features the use of an intramolecular McMurry coupling and Sharpless asymmetric epoxidation as key steps.     

Stereoselective total synthesis of (−)-pyrenophorol

An efficient stereoselective total synthesis of (−)-pyrenophorol 1 is described. The key steps involved in this synthesis are hydrolytic kinetic resolution (HKR), MacMillan α-hydroxylation, Horner-Wadsworth-Emmons (HWE) reaction, and Mitsunobu cyclization.     

Highly efficient biocatalytic resolution of cis- and trans-3-aminoindan-1-ol: syntheses of enantiopure orthogonally protected cis- and trans-indane-1,3-diamine

The efficient chemoenzymatic synthesis of enantiopure 1,3-difunctionalized indane derivatives has been achieved. The corresponding cis and trans N-protected amino alcohols were successfully resolved by acetylation using lipase B, which is a biocatalyst isolated from Candida antarctica. All the possible isomers were obtained in very good chemical yields and ee values (>99 %). The utility of these compounds was subsequently shown by the preparation of orthogonally protected cis- and trans-indane-1,3-diamine using a Mitsunobu reaction. Both enantiomers of the trans isomer and a desymmetrized cis diastereomer were prepared in enantiopure form. Complete inversion of configuration during the Mitsunobu reaction was demonstrated by a combination of NMR techniques and molecular modeling. The utility and versatility of the strategy was also demonstrated by the selective deprotection of each nitrogen atom under mild reaction conditions.     

Enantioselective total synthesis of (-)- and (+)-petrosin

The enantioselective total synthesis of (-)- and (+)-petrosin is described. The union of two key segments was executed by Suzuki-Miyaura coupling. The quinolizidine rings were stereoselectively constructed via a diastereoselective Mannich reaction and an aza-Michael reaction. The 16-membered ring was constructed by ring-closing metathesis with the second-generation Grubbs catalyst.     

Enantioselective synthesis of oseltamivir phosphate

The key steps in the enantioselective synthesis of Tamiflu include an asymmetric Diels-Alder reaction, Mitsunobu inversion using Fukuyama modified Weinreb reagent, carbamate directed epoxidation. Epoxide opening with trimethylsilyl azide furnished a 3:1 mixture of regioisomers that converged to afford the same aziridine. Attempted preparation of the unsaturated ester regioselectively using 2-iodoxybenzoic acid (IBX) following Nicolaou’s protocol failed. The unsaturated ester was prepared by phenylselenylation followed by selenoxide elimination.     

The total synthesis of (-)-callystatin A

Callystatin A is a prominent member of a class of natural products which display promising growth inhibition of cancer cells in their biological profile. The challenging structure and the interesting biological activity of (-)-callystatin A fueled our interest in the synthesis of this marine natural product. We achieved the total synthesis using a highly convergent approach joining four subunits together with a Wittig olefination, a selective Heck reaction and an aldol reaction as the pivotal steps. The aldol reaction as one of the final transformations during the synthesis opens fast access to a variety of structural analogues and circumvents tedious protecting group manipulations. Here we report an improved synthesis utilizing a modified vinyl iodide which shortens the synthesis by two steps. Additionally, first biological results will be reported.