Total synthesis of (−)-phaeosphaeride B by a biomimetic conversion from (−)-phaeosphaeride A

We have accomplished the first total synthesis of STAT3 inhibitory (?)-phaeosphaeride A and its stereoisomer (?)-phaeosphaeride B. This work confirms the configurational assignment of these natural products. Notably, TFA-mediated dehydrative stereoinversion of phaeosphaeride A afforded phaeosphaeride B, based on our hypothesis of the biosynthesis mechanism of phaeosphaeride B from phaeosphaeride A.     

Total synthesis of (−)-seimatopolide A

The total synthesis of (?)-seimatopolide A is described in a linear fashion with high yielding steps. The key reactions include Lu’s isomerization, Sharpless asymmetric dihydroxylation and Kita’s macrolactonization.     

Total synthesis of (−)-renieramycin G from l-tyrosine

(?)-Renieramycin G was synthesized in 21 steps for the longest linear sequences employing l-tyrosine methyl ester as the chiral starting material in 8.5% overall yield. Two of the four chiral centers came from l-tyrosine methyl ester, and the other two were induced through an intermolecular and an intramolecular Pictet–Spengler reaction, respectively.     

Total synthesis of (−)-lentiginosine

A simple and practical synthesis of (−)-lentiginosine 2 with good overall yield has been achieved from the commercially available diethyl d-tartarate. The key steps are a highly stereoselective Grignard reaction on an aldehyde and a Staudinger reduction.     

Total synthesis of (−)-isoaltholactone

A short and efficient stereoselective synthesis of a styryllactone (-)-isoaltholactone has been achieved in seven steps and 33% overall yield, starting from the readily available carbohydrate D-mannose. The key steps of our synthesis involve intramolecular tetrahydrofuran cyclization and one-pot acetonide deprotection-lactonization.     

Total synthesis of (−)-vindoline

In this full paper, a stereocontrolled strategy for the total synthesis of (?)-vindoline is described. This synthetic route features: 1) rapid construction of the stereochemical center at C19 through a highly diastereoselective vinylogous Mannich addition; 2) tandem Heathcock/aza-Prins cyclization to install rings C and E in vindoline; 3) oxidative transformation of β-ketoester to enone; 4) stereoselective inversion of C4 stereochemistry with triphenylphosphine and carbon tetrabromide followed by Brønsted acid.     

Total synthesis of (−)-haploscleridamine

Asymmetric total synthesis of the imidazole containing β-carboline natural product, haploscleridamine, from histidine is described. Key to the successful assembly of this alkaloid is a ring-closing metathesis reaction of an imidazole derived allylic alcohol to construct a 3-piperidinone. Application of the Buchwald-modification of the classical Fischer indolization and deprotection of the N-tosyl moiety delivered haploscleridamine.     

Total synthesis of (−)-periplanone-B,the sex pheromone of the American cockroach

The total synthesis of (−)-periplanone-B, the sex excitant pheromone of the American cockroach, Periplaneta americana is accomplished starting from (+)-limonene.     

Total synthesis of (−) verbenalol and (−) epiverbenalol

The first asymmetric synthesis of (−) verbenalol and (−) epiverbenalol, starting from the organometallic complex (−) 1, is described.     

Total synthesis of (−) altholactone (goniothalenol) from D-glucose

A ten steps total synthesis of (−) altholactone, enantiomer of an antitumor pyrone isolated from Goniothalamus species, is described starting from D-glucose.     

Stereoselective total synthesis of (−)-zeylenol,a key intermediate for the synthesis of (+)-pipoxide, (−)-uvarigranol G and (−)-tonkinenin A

Total synthesis of (?)-zeylenol, a key intermediate for the synthesis of (+)-pipoxide, (?)-uvarigranol G and (?)-tonkinenin A was achieved from commercially available starting material d-mannose. The key steps are mixed aldol condensation, Grignard reaction, ring closing metathesis and regioselective benzoylation.     

Studies on the synthesis of chiral nonracemic 3,4-disubstituted azepanes,a formal synthesis of (+)- and (−)-balanol

Sugar lactones were converted to 3,4-disubstituted azepanes and caprolactam derivatives by selective deoxygenation, functionalization and reductive cyclization. The cyclization proved troublesome with 6-azidolactols but led to good results with the corresponding lactones. A formal synthesis of (+)- and (−)-balanol is reported.     

Total synthesis of the 2,6-disubstituted piperidine alkaloid (−)-andrachcinidine

The total synthesis of the 2,6-disubstituted piperidine alkaloid (?)-andrachcinidine is reported using Keck’s asymmetric allylation, Sharpless epoxidation, nucleophilic substitution, and intramolecular aza-Michael addition as the key steps.     

Total synthesis of natural (−)- and unnatural (+)-Melearoride A

This communication details the first total synthesis of the 13-membered macrolide, (?)-Melearoride A, as well as unnatural (+)-Melearoride A. The synthesis features a concise 13 step synthesis (11 steps longest linear sequence) that offers flexible stereo-control and multiple opportunities for unnatural analog synthesis to delve into antifungal SAR. The route features a cuprate addition, an Evans asymmetric alkylation, and a ring-closing metathesis (RCM) to close the 13-membered macrocyclic core.     

A stereocontrolled synthesis of (−)-detoxinine from l-ascorbic acid

A stereoselective synthesis of (−)-detoxinine, the core unit of the detoxifying agent detoxin D₁, is presented. The approach, characterized by the use of an inexpensive starting material and by the easy and stereoselective preparation of the key 4,5-disubstituted oxazolidin-2-one 11, proves to be a suitable alternative to the known procedures.     

Total synthesis of (−)-synrotolide and the evaluation of its antiproliferative activity

The stereoselective synthesis of (−)-synrotolide was achieved in high overall yield from d-(−)-ribose and 3-butyn-1-ol. The pivotal step in this approach is the selective deprotection of the acetonide group in the presence of acetate groups using TiCl₄. Moreover, the biological activity of (−)-synrotolide was evaluated on HeLa, PANC 1, HepG2, and SK-N-SH cancer cell lines. The (−)-synrotolide selectively and potently inhibited the growth of PANC 1 cell line.     

Total synthesis of (−)-jaspine B and its 4-epi-analogue from d-xylose

The total synthesis of the HCl salts of (−)-jaspine B ent-1 and its 4-epi-congener ent-4 was accomplished starting from the common template 13 derived from d-xylose. The cornerstone of our synthesis was [3,3]-heterosigmatropic rearrangements, which effectively provided scaffolds with a chiral amino group. A subsequent Wittig olefination installed a C₁₄ alkyl side chain and acid-mediated ring-closing reaction established the tetrahydrofuran core.     

Total Synthesis of (−)-Glaucocalyxin A

A practically useful method for the formation of the highly oxygenated bicyclo[3.2.1]octane ring system through Mn(OAc)₃-mediated radical cyclization of alkynyl ketones was developed, which opens up a new avenue for the total synthesis of a number of highly oxidized diterpenoids. Application of this method enabled the first total synthesis of (−)-glaucocalyxin A. Other salient features of the synthesis include a highly enantioselective conjugate addition/acylation cascade reaction, a Yamamoto aldol reaction, and an intramolecular Diels–Alder reaction to assemble the A/B ring system.     

Stereoselective synthesis of (−)-8-epi-swainsonine starting with a chiral aziridine

An efficient synthesis of (?)-8-epi-swainsonine, starting from a commercially available 1-(R)-α-methylbenzylaziridine-2-methanol, was developed. The synthetic route utilizes stereocontrolled Sharpless asymmetric dihydroxylation governed by AD-mix-β followed by an aziridine ring opening-cyclization sequence to generate the five membered N-heterocyclic ring system present in the bicyclic target. A subsequent stereoselective allylation and piperidine ring forming cyclization then produced a precursor that was converted into (?)-8-epi-swainsonine.     

Total synthesis of (−)-cleistenolide and formal synthesis of herbarumin I via a diastereoselective modulable allylation

A modulable tin based allylation method for the synthesis of 1,2,3-triols is described. The optimization of the reaction was aided by ¹H and ¹¹⁹Sn low temperature NMR spectroscopic investigations, which support the formation of two cyclic intermediates after transmetallation. Depending on the nature of the Lewis acid, either syn/anti or anti/syn configured triols could be obtained with good stereocontrol. To demonstrate the value of this methodology and the resulting scaffolds, they were used to install the signature triol motifs of (?)-cleistenolide and of herbarumin I.