Total synthesis of herboxidiene/GEX 1A

A convergent enantioselective synthesis of herboxidiene/GEX 1A (1) is described that features a double stereodifferentiating crotylation, [4 + 2] annulation, and a silicon-based sp2-sp2 cross-coupling to assemble the conjugated diene.     

Total synthesis of GEX1A

An efficient and readily modifiable synthesis of GEX1A/herboxidiene/TAN-1609 ( 1) was developed. This modular synthesis featured a Suzuki coupling to install the conjugated diene and a Ru-catalyzed lactonization and Roush crotylation to construct the functionalized tetrahydropyran moiety. Myers' alkylation, cross-metathesis, and Keck crotylation were employed for assembly of the biologically essential side-chain domain.     

Total synthesis of (+)-herboxidiene from two chiral lactate-derived ketones

A substrate-controlled synthesis of (+)-herboxidiene from two lactate-derived chiral ketones is described. Remarkably, most of the carbon backbone was constructed through highly stereoselective titanium-mediated aldol reactions and an Ireland-Claisen rearrangement. Furthermore, an oxa-Michael cyclization and a high-yield Suzuki coupling were used to assemble the pyran ring and the diene moiety respectively.     

A stereoselective synthesis of (+)-gonyautoxin 3

An asymmetric synthesis of the paralytic shellfish poison (PSP), (+)-gonyautoxin 3, is described. A unique, Rh-catalyzed amination reaction provides rapid access to the heteratom-rich, tricyclic core of the toxin, which is common to more than 30 related natural products. The completed route should facilitate the preparation of other naturally occurring PSPs and designed analogues thereof.     

A short stereoselective synthesis of (+)-boronolide

A short and stereoselective synthesis of (+)-boronolide via oxidative functionalization of an olefin using a pendant sulfinyl group is described. Diastereoselective allylation was performed using Keck’s protocol and the lactone moiety was prepared by ring closing metathesis.     

A concise stereoselective total synthesis of (+)-artemisinin

A protective group free, concise, and stereoselective total synthesis of (+)-artemisinin, starting from readily available (R)-(+)-citronellal, is described. Asymmetric 1, 4-addition, Aldol condensation, Ene reaction, regioselective hydroboration are the key steps involved in the total synthesis of the target molecule.     

Total stereoselective synthesis of (+)-goniothalesdiol

[reaction: see text] The stereoselective synthesis of (+)-goniothalesdiol (1) was accomplished in nine steps starting from commercially available (-)-(2S,3S)-dimethyl D-tartrate (3). The key features were a completely diastereoselective reduction of a beta-ketosulfoxide to generate the stereogenic center at C-5 in 7 and formation of the 2,5-cis-substituted tetrahydrofuran ring in 10 from a stereoselective Et(3)SiH/TMSOTf-promoted reductive cyclization/deoxygenation.     

An efficient stereoselective synthesis of (+)-deoxoprosophylline

An efficient stereoselective synthesis of (+)-deoxoprosophylline from readily available p-anisaldehyde is described. Key steps in the synthesis include the stereoselective amination of anti-1,2-dibenzyl ether using chlorosulfonyl isocyanate, intermolecular olefination, and Pd-catalyzed intramolecular cyclization.     

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.     

The first stereoselective synthesis of (+)-nuciferol and (+)-nuciferal

Using (S)-benzyl 2,3-epoxypropyl ether (1), the first stereoselective synthesis of (+)-nuciferol (14) and (+)-nuciferal (16) has been achieved. Employing the same methodology an enantioselective synthesis of (+)--curcumene (17) is also described.     

First stereoselective total synthesis of (+)-dodoneine

The first stereoselective total synthesis of the natural product (+)-dodoneine is described involving a Crimmins aldol reaction and a Horner-Wadsworth-Emmons olefination as the key steps.     

A short stereoselective synthesis of (+)-aza-galacto-fagomine (AGF)

A catalytic asymmetric synthesis of (+)-aza-galacto-fagomine (AGF) – the most promising compound for the pharmacological chaperone therapy of Krabbe disease – was accomplished in six steps, in 14% overall yield. The synthesis hinges on the combination of organocatalyzed aldolization and reductive hydrazination.     

Sequential Baylis-Hillman/RCM protocol for the stereoselective synthesis of (+)-MK7607 and (+)-streptol

Sequential Baylis-Hillman/ring-closing metathesis (RCM) approach toward the total synthesis of (+)-MK7607 and (+)-streptol starting from (R,R)-tartaric acid is reported.     

A stereoselective synthesis of the C15-C25 subunit of (+)-lasonolide A

The C₁₅-C₂₅ upper THP segment 2 of (+)-lasonolide A has been synthesized efficiently via diastereomeric differentiation, iodocyclization and Julia-Kocieński's sulfone olefination to install its quaternary chiral center, cis-2,6-disubstituted THP and trans-olefin, respectively.     

A short and efficient stereoselective synthesis of the polyhydroxylated macrolactone (+)-aspicillin

[structures: see text] A short and efficient synthesis of the polyhydroxylated macrolactone (+)-aspicilin 1 using a stereoselective lithium perchlorate mediated addition of allyltributyltin to the equatorially disposed carboxaldehyde of 3 (derived from (R',R',R,S) butane diacetal protected butane tetrol 2) as the key step is described. Terminal group manipulation and Masamune-Roush olefination using phosphonate ester 4 followed by macrocyclization via ring closing metathesis afforded the natural product after partial hydrogenation and global deprotection.     

Highly stereoselective and efficient total synthesis of (+)-laurencin

A highly stereoselective and efficient asymmetric total synthesis of (+)-laurencin (1) has been accomplished from the known oxazolidinone 5 in 15 steps. The route features an efficient internal alkylation to form oxocene 3 from 4 and a novel use of acetonitrile anion as a two-carbon acetaldehyde equivalent for direct synthesis of ketone 2 from alpha-alkoxy amide 3.     

Asymmetric synthesis of (+)-iso-6-cassine via stereoselective intramolecular amidomercuration

The first asymmetric synthesis of (+)-iso-6-cassine is described. Lipase-catalyzed resolution, enantioselective Overman rearrangement, and diastereoselective intramolecular amidomercuration were used for the installation of the three stereocenters in (+)-iso-6-cassine, and cross-metathesis was employed for the attachment of the side-chain.     

A stereoselective synthesis of the C11-C19 fragment of (+)-peloruside A

A new route to the synthesis of the C11-C19 fragment of peloruside A is described, which includes an aldol reaction with ethyl acetoacetate, β-hydroxyl-directed reduction of β-hydroxy ketone, as well as methylation of C13 hydroxyl moiety in the system of MeI-Ag₂O-MgSO₄-CH₂Cl₂.     

A stereoselective synthesis of (+)-L-733,060 from ethyl (R)-(+)-2,3-epoxypropanoate

An asymmetric synthesis of neurokinin substance P receptor antagonist (+)-L-733,060 starting from enantiomerically pure ethyl (R)-(+)-2,3-epoxypropanoate (ethyl glycidate) is described. The synthesis relies on a diastereoselective reductive amination, regioselective intramolecular epoxide opening, and in situ cyclization as the key steps.     

A facile and stereoselective synthesis of the C-2 epimer of (+)-deacetylanisomycin

A short, simple and efficient synthesis of the C-2 epimer of (+)-deacetylanisomycin starting from d-mannitol, utilizing an epoxide opening with a Grignard reagent and acid catalysed unusual intramolecular 5-endo-tet cyclization as key steps has been reported.