Total syntheses of (±)-lentiginosine and (±)-1-epi-lentiginosine from hexahydro-1H-indol-3-one

Total syntheses of (±)-lentiginosine 1 and (±)-1-epi-lentiginosine 2 were achieved efficiently from hexahydro-1H-indol-3-one 7.     

Total syntheses of (±)-α-acorenol, β-acorenol, α-epi-acorenol and β-epi-acorenol via an Ireland ester Claisen rearrangement and RCM reaction sequence

Total syntheses of (±)-α- and β-acorenols and (±)-α- and β-epi-acorenols, spiro[4.5]decane sesquiterpenes, isolated from the western Australian sandalwood oil, have been accomplished employing a combination of Ireland ester Claisen rearrangement and RCM reactions for an efficient construction of the spiro[4.5]decane present in acoranes.     

Syntheses of (±)-9-epi-hederacine A and (±)-9-epi-hederacine B

Racemic syntheses of 9-epi-hederacine A and 9-epi-hederacine B have been achieved. Key transformations include a transannular hemiaminal formation for construction of the azabicyclo[3.2.1]octane core fused to a cyclopentane ring.     

Stereocontrolled total syntheses of (±)-clovan-3-one and (±)-epi-clovan-3-one and a facile total synthesis of (±)-pseudoclovene-A

Stereocontrolled total syntheses of the bridged tricyclic ketones (±)-clovan-3-one (5) and (±)-epi-clovan-3-one (6) and a facile total synthesis of the tricyclic sesquiterpene (±)-pseudoclovene-A (3) have been successfully accomplished involving participation of an aryl intramolecular cyclisation of the bromophenol 11 as a key step.     

Total syntheses of (±)-cis- and (±)-trans-neocnidilides

Total syntheses of two antimicrobial natural products (±)-cis-neocnidilide and (±)-trans-neocnidilide starting from a readily preparable cyclohexa[b]-fused 5-oxabicyclo[2.1.1]hexane derivative are presented. The diastereomeric tetrahydrofuran tricarboxylate epimers obtained from a BF₃·OEt₂ promoted Grob-type fragmentation of the oxa-bicycle derivative were converted into title natural products by employing pyridinium dichromate/acetic anhydride mediated bis-oxidative cleavage reaction.     

Total synthesis of (±)-β-chamigrene and (±)-laurencenone C via Ireland ester Claisen rearrangement and an intramolecular type II carbonyl ene reaction sequence

A combination of Ireland ester Claisen rearrangement and intramolecular type II carbonyl ene reactions were exploited for the total synthesis of chamigrenes containing a quaternary carbon atom next to the spirocentre in spiro[5.5]undecane.     

Construction of spiro[5.5]undecanes containing a quaternary carbon atom adjacent to a spirocentre via an Ireland ester Claisen rearrangement and RCM reaction sequence. Total syntheses of (±)-α-chamigrene, (±)-β-chamigrene and (±)-laurencenone C

Starting from cyclohexanecarboxylic acid, a combination of an Ireland ester Claisen rearrangement and RCM reactions was exploited for an efficient construction of spiro[5.5]undecanes containing a quaternary carbon atom adjacent to the spirocentre and the methodology was extended to complete total syntheses of three chamigrenes.     

Efficient syntheses of (±)-hydrangenol, (±)-phyllodulcin and (±)-macrophyllol

In this paper we report on a efficient and flexible synthetic route towards the total syntheses of the dihydrocoumarine derivatives hydrangenol (1), phyllodulcin (1a) and macrophyllol (6b). The syntheses started with a readily available phosphonium salt 2 and suitable modified benzaldehydes 3/3a/3b resulting in 46 to 61% overall yields in three to four-steps sequences. The racemic products could be separated by chiral HPLC. The evidence of the (R)-enantiomer for sweetness could be demonstrated for 1a.     

Total synthesis of (±)-1,13-herbertenediol, (±)-α-herbertenol and (±)-β-herbertenol

Total synthesis of α-herbertenol, β-herbertenol and 1,13-herbertenediol, employing a Claisen rearrangement and ring-closing metathesis as key reactions for the generation of the cyclopentane containing vicinal quaternary carbons, has been described.     

A general approach to crinine-type Amaryllidaceae alkaloids: total syntheses of (±)-haemanthidine, (±)-pretazettine, (±)-tazettine, and (±)-crinamine

A general strategy for synthesizing the crinine-type Amaryllidaceae alkaloids was developed. And total syntheses of four representative crinine-type Amaryllidaceae alkaloids: (±)-haemanthidine, (±)-pretazettine, (±)-tazettine, and (±)-crinamine, were accomplished via a common intermediate 17. This crucial precursor was achieved on the basis of the NBS-promoted semipinacol rearrangement recently developed by our group and an intramolecular Michael addition, which efficiently constructed the sterically congested quaternary carbon center and the hydroindole skeleton of the crinine-type alkaloids, respectively.     

Total synthesis of (±)-heliannuol C and E via aromatic Claisen rearrangement

The total synthesis of heliannuol C and E from a common intermediate are described. Key steps in the synthesis include a regioselective aromatic Claisen rearrangement to install the (1-vinyl)-4-methyl-3-pentenyl substituent and regioselective biomimetic 7-endo and 6-exo phenol epoxide cyclizations to form the cyclic ether moieties.     

Formal total synthesis of (±)-fragranol via template catalyzed 4-exo cyclization

A novel approach to the synthesis of (±)-fragranol is described that relies on a radical 4-exo cyclization. This key step is catalyzed by a cationic titanocene complex with a pending amide ligand. In this manner the radical and its acceptor are bound to the titanocene center in a two-point mode. By this interaction the 4-exo cyclization that is not supported by gem-dialkyl substitution is rendered thermodynamically and kinetically favorable. Moreover, the crucial intermediates and transition structures become highly ordered. This results in a good diastereoselectivity of cyclobutane formation. From the key-intermediate, the formal total synthesis of the natural product can be completed in a few steps.     

Total syntheses of proposed (±)-trichodermatides B and C

Total syntheses of putative (±)-trichodermatides B and C are described. These efficient syntheses feature the oxa-[3+3] annulation strategy, leading to B and C along with their respective C2-epimers. However, these synthetic samples are spectroscopically very different from the natural products. DFT calculations of C13 chemical shifts are conducted and the predicted values are in good agreement with those of synthetic samples, thereby questioning the accuracy of structural assignments of trichodermatides B and C.     

Stereoselective total synthesis of (±)-α-vetispirene, (±)-hinesol, and (±)-β-vetivone based on a Claisen rearrangement

The stereoselective total syntheses of (±)-α-vetispirene, (±)-hinesol, and (±)-β-vetivone were accomplished based on a Claisen rearrangement in an alkenyl bicyclic dihydropyran system. The most striking feature of this approach is that the Claisen rearrangement of bicyclic dihydropyran proceeds stereoselectively to provide a multi-functionalized spiro[4.5]decane, which is an efficient precursor for the synthesis of the vetivane sesquiterpenes.     

Total syntheses of lindenane-type sesquiterpenoids: (±)-chloranthalactones A, B, F, (±)-9-hydroxy heterogorgiolide, and (±)-shizukanolide E

Chloranthalactones A, B, F, 9-hydroxy heterogorgiolide, and shizukanolide E are a family of natural lindenane-type sesquiterpenoids isolated mainly from chloranthaceae. A general synthetic strategy was accomplished by us for the racemic total syntheses of the five natural products. The key steps included substrate-controlled Matteson epoxidation of ketone and highly diastereoselective intramolecular Hodgson cyclopropanation to construct the challenging cis, trans-3/5/6 tricyclic skeleton, along with a methodology developed for the γ-alkylidenebutenolide ring formation.     

Concise syntheses of (±)-dichroanone, (±)-dichroanal B, (±)-taiwaniaquinol B, and (±)-taiwaniaquinone D

The total syntheses of dichroanone and dichroanal B, as well as the formal syntheses of taiwaniaquinol B and taiwaniaquinone D, are reported.     

(±)-Diplacone与(±)-3'-O-methyldiplacone的全合成

以廉价的香草醛,3,4-二羟基苯甲醛和2,4,6-三羟基苯乙酮为初始原料,经过C-香叶基化、羟基保护、羟醛缩合、脱去保护基以及催化环化等步骤,以11%和20%的总收率实现了两个天然香叶基黄烷酮(±)-diplacone与(±)-3′-O-methyldiplaone的首次全合成,其结构经¹H NMR, IR和MS表征。     

Protecting group free syntheses of (±)-columbianetin and (±)-angelmarin

A five-step and protecting group free synthesis of (±)-columbianetin from cyclohexane-1,3-dione is reported. The former compound was converted into its p-hydroxycinnamate derivative, (±)-angelmarin, using Coster’s esterification procedure. Efforts to modify the synthesis so as to prepare angelmarin and columbianetin in an enantioselective manner are described.     

Total synthesis of (±)-stemonamide, (±)-isostemonamide, (±)-stemonamine, and (±)-isostemonamine using a radical cascade

A total synthesis of (±)-stemonamide and (±)-isostemonamide has been achieved by using a radical cascade that involves two endo-selective cyclizations. (±)-Stemonamine and (±)-isostemonamine are synthesized by chemoselective reduction of (±)-stemonamide and (±)-isostemonamide, respectively.     

First total syntheses of (±)-3-aza-11-selena and (±)-3-aza-11-tellura steroids

An efficient synthesis of 11-selena and 11-tellura steroids bearing a pyridine as an A ring was achieved via an intramolecular Diels-Alder cycloaddition of o-quinodimethanes, which were generated from a 3-azabicyclo[4.2.0]octa-1,3,5-trien-7-one ketal. The major isomer matches the trans-anti-trans ring configuration of natural products. Finally, the vinyl groups of the synthesized 11-hetero steroids have been oxidized by the Wacker process in good yields. The characteristic ¹H and ¹³C NMR spectroscopic features of the synthesized compounds are reported.