Total Synthesis of (±)‐Boonein

A total synthesis of (±)‐boonein ( 8 ) from bicyclo[2.2.1]ketone 9 is described. Bicyclo[3.2.1]lactone 10 is the key intermediate.     

A Concise Total Synthesis of (±)‐Vibralactone

Disclosed is a five‐step synthesis of (±)‐vibralactone, a biologically active terpenoid natural product. A key photochemical valence isomerization of 3‐prenyl‐pyran‐2‐one produces both the all‐carbon quaternary stereocenter and the β‐lactone at an early stage. Cyclopropanation of the resulting bicyclic β‐lactone produces a strained housane structure that is converted to the natural product through a sequential ring expansion and reduction strategy. This concise and modular route to the natural product provides the shortest total synthesis of (±)‐vibralactone reported to date.     

Total Synthesis of (±)‐Alstoscholarisine A

The first total synthesis of the neuroactive indole alkaloid (±)‐alstoscholarisine A is reported. The key step of the concise synthesis is an efficient domino sequence that was used to assemble the 2,8‐diazabicyclo[3.3.1]nonane core through the formation of two C?N bonds and one C?C bond in a single step.     

Total Synthesis of (±)‐Corymine

The first total synthesis of the hexacyclic indole alkaloid (±)‐corymine is described. Starting from the readily available N‐protected tryptamine, the title compound was achieved in 21 steps in 3.4 % overall yield. Key steps of the synthesis include: a) the addition of a malonate to a 3‐bromooxindole to afford 3,3‐disubstituted oxindole, b) the formation of a 12‐membered cyclic enol ether by intramolecular O‐propargylation, immediately followed by propargyl Claisen rearrangement to provide the α‐allenyl ketone stereospecifically, c) DMDO oxidation to install a hydroxy group in a highly stereoselective manner, and d) the SmI₂‐mediated reductive C−O bond cleavage to remove the α‐keto carboxyl group.     

Facile Total Synthesis of (±)‐Nimbiol

A facile total synthesis of (±)‐nimbiol 1 has been achieved. In order to decrease the dioxo byproduct 2a , an improved oxidation system of CrO₃/H₂O/HOAc/NaOAc was used.     

Total Synthesis of (-)-Kaerophyllin,(-)-Hinokinin and (±)-Isohinokinin

Kaerophyllin (1) ,hinokinin (2 )andtheiranalogue isohinokinin (3)belongtothedibenzylbutyrolactone lig nans .Kaerophyllin (1)wasisolatedfromtherootofspot tedcowparsley (ChaerophyllummaculatumWilld .) 1andhinokinin (2 )wasisolatedfromtheheartwoodofLiboce drusformosanaFlorin .2 AccordingtoMacRaeandTow ers ,3afivememberedlactoneringandamethylenedioxylgroupwereimportantstructuralcharacteristicswhichcon tributetotheactivityoflignansasantitumoragents .More over ,anunsaturateddoublebondbetweenC3—…     

First Total Synthesis of (±)‐Celaphanol A

The first total synthesis of (±)‐Celaphanol A was accomplished starting from α‐cyclocitral and 3,4‐dimethoxy benzyl chloride in six steps. The intramolecular cyclization with BF₃·Et₂O and enolization in t‐BuOK/t‐BuOH were the key steps. The process of intramolecular cyclization afforded an all‐cis isomer intermediate for synthesis of aromatic tricyclic diterpenes.     

Total Synthesis of (±)‐Hippolachnin A

The first total synthesis of the marine polyketide (±)‐hippolachnin A has been achieved in nine linear steps and an overall yield of 9 %. Rapid access to the oxacyclobutapentalene core structure was secured by strategic application of an ene cyclization.     

A Bioinspired Synthesis of (±)‐Rubrobramide, (±)‐Flavipucine,and (±)‐Isoflavipucine

A biomimetic synthesis of naturally occurring lactams rubrobramide, flavipucine, and isoflavipucine is described. The key step is a regioselective Darzens reaction between isobutyl glyoxal and an α‐bromo‐β‐ketoamide. The construction of the core tricyclic ring system of rubrobramide was achieved by a cascade reaction in a single step from an α,β‐epoxy‐γ‐lactam. Furthermore, the absolute configuration of naturally occurring (+)‐rubrobramide was determined by vibrational circular dichroism. (±)‐Flavipucine and (±)‐isoflavipucine were synthesized from an epoxyimide, which was prepared by reaction of isobutyl glyoxal with a protected α‐bromo‐β‐ketoamide. Deprotection of the epoxyimide and formation of the pyridone ring gave (±)‐flavipucine, which was converted into (±)‐isoflavipucine by thermal isomerization.     

Synthesis of (±)‐Nephromopsinic, (−)‐Phaseolinic,and (−)‐Dihydropertusaric Acids

The formal syntheses of (±)‐nephromopsinic acid, (−)‐phaseolinic acid, and the first total synthesis of (−)‐dihydropertusaric acid from (±)‐ and (−)‐7‐oxabicyclo[2.2.1]hept‐5‐en‐2‐one are described. These syntheses take advantage of a previously reported radical rearrangement (1,2‐acyl migration). A remarkable iodide‐mediated cleavage of a bicyclic system, followed by the introduction of the γ‐chains via a mixed Kolbe electrolysis, are the key steps of these syntheses. This approach is general and could be applied for the preparation of all kinds of paraconic acids with excellent control of the stereochemistry.     

Total Synthesis of (±)‐Gephyrotoxin by Amide‐Selective Reductive Nucleophilic Addition

A chemoselective approach for the total synthesis of (±)‐gephyrotoxin has been developed. The key to success was the utilization of N‐methoxyamides, which enabled the direct coupling of the amide with an aldehyde and selective reductive nucleophilic addition to the amide in the presence of a variety of sensitive and electrophilic functional groups, such as a methyl ester. This chemoselective approach minimized the use of protecting‐group manipulations and redox reactions, which resulted in the most concise and efficient total synthesis of (±)‐gephyrotoxin described to date.     

Total Synthesis of (±)‐Phomoidride D

Described herein is a synthetic strategy for the total synthesis of (±)‐phomoidride D. This highly efficient and stereoselective approach provides rapid assembly of the carbocyclic core by way of a tandem phenolic oxidation/intramolecular Diels–Alder cycloaddition. A subsequent SmI₂‐mediated cyclization cascade delivers an isotwistane intermediate poised for a Wharton fragmentation that unveils the requisite bicyclo[4.3.1]decene skeleton and sets the stage for synthesis completion.     

A Bioinspired Synthesis of (±)‐Rubrobramide, (±)‐Flavipucine,and (±)‐Isoflavipucine

A biomimetic synthesis of naturally occurring lactams rubrobramide, flavipucine, and isoflavipucine is described. The key step is a regioselective Darzens reaction between isobutyl glyoxal and an α‐bromo‐β‐ketoamide. The construction of the core tricyclic ring system of rubrobramide was achieved by a cascade reaction in a single step from an α,β‐epoxy‐γ‐lactam. Furthermore, the absolute configuration of naturally occurring (+)‐rubrobramide was determined by vibrational circular dichroism. (±)‐Flavipucine and (±)‐isoflavipucine were synthesized from an epoxyimide, which was prepared by reaction of isobutyl glyoxal with a protected α‐bromo‐β‐ketoamide. Deprotection of the epoxyimide and formation of the pyridone ring gave (±)‐flavipucine, which was converted into (±)‐isoflavipucine by thermal isomerization.     

Total Synthesis of (±)‐Integrifolin

The total synthesis of (±)‐integrifolin has been achieved for the first time through the stereoselective preparation of the bicyclo[5.3.0]decane skeleton based on the tungsten‐catalyzed cyclization of acyclic trienynes under photoirradiation conditions. Further key transformations of the cyclized product are the Tamao oxidation through cyclic silyl ether, the introduction of two oxygen functionalities by the oxidation of the diene and the construction of three exo‐methylene moieties.     

(±)-Palstatin的首次全合成研究

以廉价易得的5-溴香草醛和2,4,6-三羟基苯乙酮为起始原料，首次方便,高效地合成了(±)-Palstatin (1).合成的关键步骤为SeO₂促进的氧化环化和Ag₂O催化的氧化偶联反应.     

Total Syntheses of (±)‐Fawcettimine, (±)‐Fawcettidine, (±)‐Lycoflexine,and (±)‐Lycoposerramine‐Q

The total syntheses of four fawcettimine‐related Lycopodium alkaloids, (±)‐fawcettimine, (±)‐fawcettidine, (±)‐lycoposerramine‐Q, and (±)‐lycoflexine, were completed in a highly stereoselective manner. The Pauson–Khand reaction of 4‐methylidene‐6‐siloxyoct‐1‐en‐7‐yne followed by regio‐ and stereoselective hydrogenation led to the short‐step preparation of the bicyclo[4.3.0]nonenone intermediate bearing a methyl group with the required stereochemistry. The subsequent chemical manipulation of the bicyclic compound afforded the 6‐5‐9‐membered tricyclic dioxo compound, which was then transformed into the four targeted alkaloids in an alternative and more efficient fashion.     

Collective Total Syntheses of Atisane‐Type Diterpenes and Atisine‐Type Diterpenoid Alkaloids: (±)‐Spiramilactone B, (±)‐Spiraminol, (±)‐Dihydroajaconine,and (±)‐Spiramines C and D

The first total syntheses of the architecturally complex atisane‐type diterpenes and biogenetically related atisine‐type diterpenoid alkaloids (±)‐spiramilactone B, (±)‐spiraminol, (±)‐dihydroajaconine, and (±)‐spiramines C and D are reported. Highlights of the synthesis include a late‐stage biomimetic transformation of spiramilactone B, a facile formal lactone migration from the pentacyclic skeleton of spiramilactone E, a highly efficient and diastereoselective 1,7‐enyne cycloisomerization to construct the functionalized tetracyclic atisane skeleton, and a tandem retro‐Diels–Alder/intramolecular Diels–Alder sequence to achieve the tricyclo[6.2.2.0] ring system.     

Collective Total Syntheses of Atisane‐Type Diterpenes and Atisine‐Type Diterpenoid Alkaloids: (±)‐Spiramilactone B, (±)‐Spiraminol, (±)‐Dihydroajaconine,and (±)‐Spiramines C and D

The first total syntheses of the architecturally complex atisane‐type diterpenes and biogenetically related atisine‐type diterpenoid alkaloids (±)‐spiramilactone B, (±)‐spiraminol, (±)‐dihydroajaconine, and (±)‐spiramines C and D are reported. Highlights of the synthesis include a late‐stage biomimetic transformation of spiramilactone B, a facile formal lactone migration from the pentacyclic skeleton of spiramilactone E, a highly efficient and diastereoselective 1,7‐enyne cycloisomerization to construct the functionalized tetracyclic atisane skeleton, and a tandem retro‐Diels–Alder/intramolecular Diels–Alder sequence to achieve the tricyclo[6.2.2.0] ring system.     

Concise Stereoselective Synthesis of Oxaspirocycles with 1‐Tosyl‐1,2,3‐triazoles: Application to the Total Syntheses of (±)‐Tuberostemospiroline and (±)‐Stemona‐lactam R

A 4‐substituted‐1‐tosyl‐1,2,3‐triazole‐based stereoselective synthesis of structurally diverse oxaspirocycles is reported. The synthesis involves Rh‐catalyzed loss of nitrogen from 4‐substituted‐1‐tosyl‐1,2,3‐triazoles, Grignard reaction, and a ring‐closing metathesis reaction as key steps. By employing readily available and stable 4‐substituted‐1‐tosyl‐1,2,3‐triazoles as surrogates of diazo compounds and nitrogen sources, two types of oxaspirocycles were obtained. The latter compounds, which contain adjacent nitrogen stereocenters, could serve as the core structures of many natural products. This chemistry has been successfully applied to the total syntheses of (±)‐tuberostemospiroline and (±)‐stemona‐lactam R.     

A Cascade Strategy Enables a Total Synthesis of (±)‐Morphine

Morphine has been a target for synthetic chemists since Robinson proposed its correct structure in 1925, resulting in a large number of total syntheses of morphine alkaloids. Here we report a total synthesis of (±)‐morphine that employs two key strategic cyclizations: 1) a diastereoselective light‐mediated cyclization of an O‐arylated butyrolactone to form a tricyclic cis‐fused benzofuran and 2) a cascade ene–yne–ene ring closing metathesis to forge the tetracyclic morphine core. This approach enables a short and stereoselective synthesis of morphine in an overall yield of 6.6 %.