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 synthesis of (±)-brazilin and formal synthesis of (±)-brazilein, (±)-brazilide A using m-CPBA

Total synthesis of (±)-brazilin has been accomplished. m-CPBA epoxidation of allyl alcohol 10 and epoxy opening reaction mediated by m-chlorobenzoic acid, formed in situ as a byproduct, gave advanced intermediate diol 14. O-alkylation and cyclization gave phenol 6 which enabled the formal synthesis of (±)-brazilein and (±)-brazilide A.     

(±)-3,5-二羟基-7,4′-二甲氧基二氢黄酮醇和(±)-3,5,7-三羟基-4′-甲氧基二氢黄酮醇的全合成

3,5 -二羟基 - 7,4′-二甲氧基二氢黄酮醇 ( 1 )从 Cephalanthus spathelliferus中分离得到后 [1] ,又在H aplopappus bayahuen[2 ] 和 L annea coromandelica[3] 等植物中被发现 ,在印度一直被用于治疗象皮病、阳痿、溃疡、阴道炎、口臭、痢疾和风湿病等 . 3,5 ,7-三羟基 - 4′-甲氧基二氢黄酮醇 ( 2 )首次从 Prunusdonestica[4 ] 中分离出来后 ,又从 Salix caprea L.,Brazilian propolis中得到 .研究表明 ,该化合物具有抗菌、抗肿瘤活性 .我们用与文献 [5 ]类似的方法以 2 ,4,6-三羟基苯乙酮和茴香醛为起始原料 ,经选择性保护、缩合、…     

Construction of vicinal quaternary carbon atoms by Ireland ester Claisen rearrangement: total synthesis of (±)-herbertenolide, (±)-herberteneacetal, (±)-herbertene-1,14-diol and (±)-herbertene-1,15-diol

Efficient total syntheses of the herbertane sesquiterpene title compounds have been accomplished employing an Ireland ester Claisen rearrangement and ring-closing metathesis reaction sequence based strategy for the construction of two stereogenic vicinal quaternary carbon atoms on a cyclopentane.     

First total synthesis of (±)-puyanin and (±)- 4′-O-methylbonannione

A facile approach for the first total synthesis of two naturally occurring geranylated flavonoids, (±)-puyanin 1 and (±)-4′-O-methylbonannione 2 have been obtained with total yield 27% and 21%, respectively. The key steps were regioselective cyclization of geranylated tetrahydroxychalcone and regioselective geranylation of 2, 4, 6-trihydroxy- acetophenone.     

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.     

Efficient formal synthesis of (±)-axamide-1 and (±)-axisonitrile-1 via an intramolecular Hosomi-Sakurai reaction

A formal synthesis of (±)-axamide-1 and (±)-axisonitrile-1 was achieved by using an intramolecular Hosomi-Sakurai reaction of the allylsilane derivative, as a key step, in which [(3-but-3-en-1-yl-3-methylcyclohex-1-en-1-yl)methyl](trimethyl)silane was transformed to a bicyclic compound possessing a core carbon framework under the oxidative dihydroxylation reaction conditions, in one step.     

Synthetic studies of furanosesquiterpenoid tetrahydrolinderazulenes. Total synthesis of (±)-echinofuran

Echinofuran (1) was isolated in 1992 and was reported to inhibit cell division of fertilized sea urchin eggs. The synthesis of 1 was achieved by a Ring A→Ring AC→Ring ABC approach employing 3-methyl-4-(trimethylsilyl)furan (2) as a precursor. A Suzuki coupling reaction and a Lewis acid mediated Friedel-Crafts cyclization were the other key steps in the construction of the ring systems. In other preliminary model studies, two furan-containing 5,7,5-fused tricyclic molecules were also realized.     

天然产物(±)-Lupinine和(±)-Epilupinine的简便合成

羽扇豆碱和表羽扇豆碱是典型的喹诺里西啶类生物碱。以哌啶酸乙酯盐酸盐为原料,通过氮烷基化反应、迪克曼缩合反应、Krapcho脱羰反应、Wittig反应等4步反应制得关键中间体5,总产率46.7%。化合物5可经文献转化,完成(±)-lupinine和(±)-epilupinine的合成。该合成方法具有合成路线短,产率高以及操作简单等优点。      

Applications of NHC-mediated O- to C-carboxyl transfer: synthesis of (±)-N-benzyl-coerulescine and (±)-horsfiline

NHC-promoted O- to C-carboxyl transfer of 3-allyl indolyl phenyl carbonates generates 3-allyl-3-phenoxycarbonyl-oxindoles with good catalytic efficiency, which are readily converted into (±)-N-benzyl-coerulescine and (±)-horsfiline.     

Formal synthesis of (±)-brazilin and total synthesis of (±)-brazilane

A convergent synthesis towards (±)-brazilin and (±)-brazilane has been reported from 3,4-dimethoxy benzaldehyde in <15 reaction steps. Palladium(II)-catalysed intramolecular Friedel–Crafts cyclisation and Lewis acid supported intermolecular Friedel–Crafts alkylation reactions have been demonstrated. A tetracyclic substituted indane common key intermediate is employed to furnish the desired two molecules in good to excellent yield. Pd(OH)₂ has played a crucial role in the total synthesis of (±)-brazilane.     

Stereocontrolled total synthesis of (±)-pisiferol and (±)-pisiferal

The stereoselective total synthesis of (±)-pisiferol (1) and (±)-pisiferal (2) has been successfully accomplished using the trans-octahydrophenanthrene derivative 20 as a key intermediate. Intramolecular cyclisation of the diazoketone 15 followed by catalytic hydrogenation provided, stereoselectively, the keto-ester 17 which was converted into the acetate 20 through the intermediates 18 and 19.     

Protoilludane sesquiterpenes: synthesis of (±)-cerapicol, formal synthesis of (±)-sterpurene, and synthesis and absolute configuration of (+)-cerapicol

New approaches to the protoilludane sesquiterpenes (±)-cerapicol and (±)-sterpurene via rearrangement routes are described. The absolute configuration of (+)-cerapicol has been determined and found in accord with a biosynthesis of the natural product via cyclization of humulene to the so-called protoilludyl cation and a subsequent 1,2-alkyl shift.     

Titanocene(III) chloride mediated radical-induced synthesis of 3,4-dihydroisocoumarins: synthesis of (±)-hydrangenol, (±)-phyllodulcin, (±)-macrophyllol and (±)-thunberginol G

A radical-promoted synthesis of 3,4-dihydroisocoumarins has been achieved in moderate to good yields using titanocene(III) chloride (Cp₂TiCl) as the radical initiator. The total synthesis of four naturally occurring dihydrocoumarins hydrangenol, phyllodulcin, macrophyllol and thunberginol G has been accomplished using the radical technology. Cp₂TiCl was prepared in situ from commercially available titanocene dichloride (Cp₂TiCl₂) and Zn-dust in THF under argon.     

Total synthesis of (±)-herbertenediol

A formal total synthesis of the sesquiterpene (±)-herbertenediol and its dimers mastigophorenes A-D has been accomplished, starting from vanillin via 2,3-dimethoxy-5-methylbenzaldehyde. A combination of Claisen rearrangement and ring-closing metathesis reactions were employed for the generation of the two vicinal quaternary carbons on a cyclopentane ring.     

One-step biomimetic synthesis of (±)-linderaspirone A and (±)-bi-linderone

A one-step biomimetic synthesis of racemic linderspirone and bi-liderone from methyllinderone has been achieved, which probably reflects the biosynthesis of the natural products. There are few naturally occurring substances that appear to be formed by a [4+4] or [4+2] cycloaddition. We proposed that the [4+4] dimerization of methyllinderone proceeds via a stepwise mechanism involving a diradical intermediate.     

Total synthesis of (±)-debromoflustramine B and E and (±)-debromoflustramide B based on one-pot intramolecular Ullmann coupling and Claisen rearrangement

Total syntheses of (±)-debromoflustramine B and E and (±)-debromoflustramide B were accomplished using a common and versatile intermediate spirocyclic oxindole 14, which was concisely prepared through intramolecular Ullmann coupling and Claisen rearrangement from iodoindole 13 on a multigram scale.     

Synthetic studies towards furosesquiterpenoids: total synthesis of (±) desmethylpallescensin-A, (±) isopallescensin-A and (±) isopallescensin-1

A new approach for a short and efficient synthesis of common cyclohexenone intermediate towards the total synthesis of some furosesquiterpenes and their analogues are described. Regioselective alkylation of Hagemann's ester with 2/3-furyl-2-ethyl bromide followed by hydrolysis cum in situ decarboxylation and 1,4-addition with Gilman's reagent produced the cyclohexanone derivatives which have been utilized for total synthesis of (±) isopallescensin-A, (±) 10-desmethylpallescensin-A, (±) 5-desmethyl-4,5-dehydromicrocionin-1 and (±) isopallescensin-1.     

A new route to eremophilanes: synthesis of (±)-eremophilenolide, (±)-eremophiledinone, and (±)-deoxyeremopetasidione

A new and efficient route to the family of eremophilanes is reported. Key steps are the highly stereocontrolled Diels-Alder reaction and aldol condensation to furnish a cis-decalin system with the desired stereochemistry present in the eremophilane family of natural products. This approach is general and was utilized for the synthesis of (±)-eremophilenolide, (±)-eremophiledinone, and (±)-deoxyeremopetasidione.     

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.