Stereoselective Total Synthesis of Stagonolide C

A convergent and efficient total synthesis of stagonolide C ( 1 ), a phytotoxic metabolite, was achieved (Schemes 2 and 3) The synthesis exploited the high configuration control in the Prins cyclization along with alkene rearrangement and ring‐closing metathesis as key steps.     

Stereoselective Total Synthesis of Stagonolide E

An efficient and highly stereoselective synthesis of stagonolide E ( 1 ) starting from the readily available hexane‐1,6‐diol ( 8 ) was accomplished, employing MacMillan α‐hydroxylation, Horner? Wadsworth? Emmons olefination, (Z)‐selective Still? Gennari olefination, and Yamaguchi lactonization as key steps.     

Asymmetric Total Synthesis of Stagonolide F

A highly convergent stereoselective total synthesis of stagonolide F is described starting from commercially available 5-hexen 1-ol using asymmetric dihydroxylation, Jacobsen^'s hydrolytic kinetic resolution (HKR), regioselective epoxide ring opening with vinyl Grignard reaction, esterification, and ring-closing metathesis (RCM) as key steps.     

Stereoselective Total Synthesis of Rugulactone

The stereoselective synthesis of the naturally occurring dihydropyranone rugulactone has been accomplished starting from 3‐phenylpropan‐1‐ol employing Maruoka allylation and ring‐closing metathesis as the key steps.     

Total Synthesis of (±)‐Infuscol A and (±)‐Cuprenenol

Abstract

Total synthesis of the nonaromatic cuparenoid sesquiterpenes (±)‐infuscol A and cuprenenol, and (±)‐infuscol B and neocuprenenol isolated from the Japanese liverwort Jungermannia infusca has been accomplished. Two ring‐closing metathesis reaction based strategies have been developed for the generation of the key intermediate of the sequence.     

铜盐催化氧化环己烯的开环加成反应

研究了一系列铜盐催化的氧化环己烯与苯基氯化镁的开环加成反应。发现Cu(OTf)2[三-氟甲磺酸铜(Ⅱ)]为催化剂时,反应能够以95％的产率得到反式-2-苯基环己醇。应用了多种代表性的手性双齿配体与Cu(OTf)2形成的配合物,催化氧化环己烯与苯基氯化镁的开环加成反应,得到很低的对映选择性。根据实验的结果建议了反应的催化循环机理。     

Total Synthesis of (−)‐Cleistenolide

An efficient and short total synthesis of (?)‐cleistenolide ( 1 ) from D ‐mannitol with an overall yield of 23.6% is described. The chiron approach for the synthesis of (?)‐cleistenolide involves a one‐C‐atom Wittig olefination, a selective allylic triethylsilyl protection, and a Grubbs‐catalyzed ring‐closure‐metathesis (RCM) reaction as the key steps.     

Stereoselective Total Synthesis of Botryolide E

The stereoselective total synthesis of the naturally occurring γ‐lactone derivative botryolide E ( 1 ) was accomplished with acetaldehyde as the starting material (Scheme 2). The asymmetric allyl boration, asymmetric dihydroxylation, chelation‐mediated diastereoselective vinylation, and ring‐closing metathesis reaction are the key steps. The method can conveniently be utilized for the preparation of other related γ‐lactone derivatives.     

Grignard reagent induced tandem semipinacol rearrangement/ketone addition reaction of 20S-hydroxy-5α-pregnane-16(17)-epoxide

A Grignard reagent induced tandem semipinacol rearrangement/chelation-controlled ketone addition process, which converts 20S-hydroxy-5α-pregnane-16(17)-epoxide into an unusual C20-substituted 17S-pregnane-3S,16R,20S-triol, is described.     

Stereoselective Total Synthesis of Mangiferaelactone using D‐Mannose as a Chiral Pool

A convergent total synthesis of mangiferaelactone has been accomplished in a highly stereoselective manner from readily available D ‐mannose. The following methods like organocatalytic enantioselective epoxidation, ring‐closing metathesis, and Steglich esterification have been employed as key steps, which make this approach more attractive.     

Toward a synthesis of the antitumor macrolide peloruside A: a chiral pool approach for the C(1)-C(11) segment

Dihydroxylation of the glucose derived α,β-unsaturated lactones 6 and 13 was found to be on the α-face of the pyranolactone ring exclusively. The resulting dihydroxylated compound from 13 has been used in a synthesis of the lactone 4, which corresponds to C(1)-C(11) of peloruside A.     

Synthesis of substituted butenolides by the ring closing metathesis of two electron deficient olefins: a general route to the natural products of paraconic acids class

A variety of allyl acrylates possessing electron-withdrawing groups undergo RCM using the second generation Grubbs’ catalyst in the presence of a Lewis acid resulting in diverse butenolides in high isolated yields. This methodology provides a general route to the natural products of paraconic acids class, exemplified by a total synthesis of (±)-phaseolinic acid.     

Stereoselective Total Synthesis of Multiplolide A and of a Diastereoisomer

A stereoselective total synthesis of multiplolide A ( 1 ) and of its diastereoisomer 2 was described from easily accessible starting materials (Schemes 2–4). The synthetic strategy involves a Jacobsen resolution, Sharpless epoxidation, Swern oxidation, Yamaguchi reaction, and ring‐closing metathesis (RCM).     

Synthesis of N‐Tosylhomosphinganine and N‐Tosylsedridine

A straightforward synthesis of N‐tosylhomosphinganine and N‐tosylsedridine has been achieved from trans‐4‐hydroxyproline by Grignard addition, regioselective Baeyer‐Villiger reaction, cross or ring‐closing metathesis and hydrogenation as the key steps.     

Synthesis of 1,2-azidoalcohols from epoxides using a task-specific protic ionic liquid: 1-hydrogen-3-methylimidazolium azide

A task-specific ionic liquid as an environmentally eco-friendly green catalyst has been synthesized and used in the ring opening of epoxides under green conditions. In order to use protic ionic liquids (PIL), we decided to synthesize 1,2-azidoalcohols via a ring opening reaction of epoxides with 1-hydrogen-3-methylimidazolium azide ([Hmim]N₃), which actually acts as a solvent, a reagent and an activator of the epoxide ring. The reaction was carried out in short times (50–70 min) at 70 °C to give 1,2-azidoalcohol in 80–94% isolated yields.     

Total Synthesis of Nonenolide

A novel synthetic route has been reported for the synthesis of nonenolide. The syntheses of fragments were initiated from commercially available and inexpensive starting materials. The synthesis involves key steps like Sharpless epoxidation, Jacobsen's resolution, lactonization, and cross‐metathesis.     

Stereoselective Total Synthesis of Dodoneine

A simple and highly efficient stereoselective total synthesis of dodoneine ( 1 ), a naturally occurring bioactive 5,6‐dihydro‐2H‐pyran‐2‐one, was achieved. The synthesis involved Keck's asymmetric allylation, iodine‐induced electrophilic cyclization, and Grubbs' catalyzed ring‐closing metathesis as key steps.     

Synthesis and Evaluation of the Cytotoxicities of Neoflavenes

The synthesis of neoflavene and neoflavenes with methoxy substituents at different positions are described. As starting materials, various salicylaldehydes were run through sequential reactions such as O‐allylation, Grignard reaction, oxidation, Wittig reaction, and ring‐closing metathesis to yield the target neoflavenes in good yield. Among the prepared neoflavenes, 7‐methoxy‐4′‐methoxyneoflavene ( 6e ) and 8‐methoxy‐4′‐methoxyneoflavene ( 6f ) exhibiting potential cell toxicities against various cells were disclosed. In particular, 6f which exhibited an IC₅₀ value of 6.5 ± 2.0 and 5.1 ± 1.1 μM against gastric carcinoma and lung carcinoma cells in vitro was found, respectively. Meanwhile, the structure and activity relationship of our synthesized neoflavenes is further discussed briefly.     

环丁烯酮化合物高效合成喹啉衍生物的应用研究

在酸催化作用下,成功实现了3-氨基-2-环丁烯酮开环重排一步合成喹啉类化合物,对反应溶剂、催化剂、温度、投料比等影响因素进行了考察,在优化反应条件下催化合成了一系列喹啉类化合物,获得了较好的产率.该合成方法具有反应温度低、产率高以及反应迅速等优点,为喹啉类衍生物的合成建立了一种简单有效的新方法.