Alkaloids from flowers of Erythrina corallodendron

Two new Erythrina alkaloids, 10-oxo-erythrinine (1) erythrinine N-oxide (2) together with 23 known ones were obtained from the flowers of Erythrina corallodendron. The structures were determined based on analysis of their spectroscopic data. All compounds were first isolated from plants of Erythrina corallodendron.     

Synthesis of (+)-(3R,5R)-3-Hydroxy-5-decanolide and Massoialactone,and Formal Synthesis of Verbalactone

Total synthesis of (3R, 5R)-(+)-3-hydroxy-5-decanolide (1) and massoialactone (2), and formal synthesis of verbalactone (3), have been reported.     

Total Synthesis of Tetrahydroquinoline Alkaloid （＋）-Angustureine

( )-(S)-Angustureine was synthesized using a CuI-catalyzed coupling reaction of iodobenzene with an enantiopure β-amino ester as the key step. The overall yield is 36% in 7 linear steps.     

吲哚生物碱(+)-Alsmaphorazine D的不对称全合成及其绝对构型更正

通过无痕手性转移策略实现了(+)-alsmaphorazine D的首次不对称全合成, 并对其绝对构型进行了更正. 该高效合成路径的关键步骤主要包括催化氧化环合反应、非对映选择性氧化缩醛胺化环合反应以及分子内自由基环合反应.     

Total synthesis of(+)-lentiginosine via a key Au catalysis

Total syntheses of(+)-lentiginosine and its 8a-epimer using a gold-catalyzed oxidative cyclization as the key step were realized.The gold chemistry,reported previously in a 4+2 synthesis of piperidin-4-ones,tolerates functionalized structures and is compatible with several protecting strategies albeit with low diastereose lectivities.     

Synthetic Studies of the Zoanthamine Alkaloids: Total Synthesis of Zoanthenol Based on an Isoaromatization Strategy

The total synthesis of zoanthenol, a unique aromatic member of the zoanthamine alkaloids, which has exhibited potent anti‐platelet activities on human platelet aggregation, is described in full detail. The key step involves a Brønsted acid‐promoted isoaromatization in the AB ring system to install the crucial aromatic ring. We have not only succeeded in the first total synthesis of zoanthenol, but also established an alternative efficient synthetic route from the commercially available norzoanthamine hydrochloride to zoanthenol.     

Chemoenzymatic Synthesis of Advanced Intermediates for Formal Total Syntheses of Tetrodotoxin

Advanced intermediates for the syntheses of tetrodotoxin reported by the groups of Fukuyama, Alonso, and Sato were prepared. Key steps include the toluene dioxygenase mediated dihydroxylation of either iodobenzene or benzyl acetate. The resulting diene diols were transformed into Fukuyama's intermediate in six steps, into Alonso's intermediate in nine steps, and into Sato's intermediate in ten steps.     

Collective Total Synthesis of 4-Azafluorenone Alkaloids

4-Azafluorenones are typically obtained by acid-mediated cyclization of 2-arylnicotinates. However, this approach fails to give 5-oxygenated 4-azafluorenones due to lactonization of 2-(2-alkoxy)phenylnicotinate intermediates. Herein, we report two modifications of established approaches to 4-azafluorenone synthesis that, either in combination or by themselves, enable the flexible preparation of 4-azafluorenones with diverse oxygenation patterns in the benzenoid ring. Undesired lactonization was circumvented via tert-butyl hydroperoxide (TBHP)-mediated radical cyclization of 2-aryl-3-(hydroxymethyl)pyridines. In the absence of suitable protecting groups for phenolic intermediates, bromide substituents were regioselectively introduced as latent hydroxy groups and later converted under palladium catalysis. We present the first total syntheses of five 4-azafluorenone alkaloids muniranine, darienine, 5,8-dimethoxy-7-hydroxyonychine, 5,6,7,8-tetramethoxyonychine, and 6,8-dihydroxy-7-methoxyonychine in addition to new total syntheses of six 4-azafluorenone alkaloids and one related pyridocoumarin alkaloid.     

Enantioselective Total Synthesis of (+)‐Neostenine

A chirality transfer approach using acyclic polyol intermediates for the synthesis of (+)‐neostenine ( 1 ) has been developed. The sequential Overman/Claisen rearrangement of an allylic 1,2‐diol was especially useful, installing two contiguous stereocenters with complete diastereoselectivity in a one‐pot sequence. The SmI₂‐mediated cyclization and the subsequent chemoselective reduction of a lactam moiety accomplished the first enantioselective total synthesis of (+)‐neostenine ( 1 ).     

抗肿瘤活性四氢异喹啉生物碱全合成研究进展

综述了近年来抗肿瘤活性四氢异喹啉生物碱Renieramycin,Ecteinascidin和Quinocarcin的全合成研究进展,对其构环顺序和方法进行了分析,对部分合成路线的优缺点进行了讨论.     

Catalytic Asymmetric Torgov Cyclization: A Concise Total Synthesis of (+)‐Estrone

An asymmetric Torgov cyclization, catalyzed by a novel, highly Brønsted acidic dinitro‐substituted disulfonimide, is described. The reaction delivers the Torgov diene and various analogues with excellent yields and enantioselectivity. This method was applied in a very short synthesis of (+)‐estrone.     

Formal Total Synthesis of Aliskiren

The efficient and selective formal total synthesis of aliskiren is described. Aliskiren, a renin inhibitor drug, has received considerable attention, primarily because it is the first of the renin inhibitor drugs to be approved by the FDA. Herein, the formal synthesis of aliskiren by iridium‐catalyzed asymmetric hydrogenation of two allylic alcohol fragments is reported. Screening a number of N,P‐ligated iridium catalysts yielded two catalysts that gave the highest enantioselectivity in the hydrogenation, which gave the saturated alcohols in 97 and 93 % ee. In only four steps after hydrogenation, the fragments were combined by using the Julia–Kocienski reaction to produce late‐stage intermediate in an overall yield of 18 %.     

Synthetic Studies of the Zoanthamine Alkaloids: The Total Syntheses of Norzoanthamine and Zoanthamine

Highly effective : We report herein the first and highly efficient total syntheses of norzoanthamine and zoanthamine in full detail, which involves stereoselective synthesis of the requisite triene for an intramolecular Diels–Alder reaction via three‐component coupling reactions, the intramolecular Diels–Alder reaction, and subsequent crucial bis‐aminoacetalization as the key steps.

     

天然产物Modhephene的全合成研究进展

综述了近年来天然产物Modhephene的全合成方法,并依据其不同的环化方法分为两大类,对每例合成方法进行了详尽的分析。     

Total Synthesis of Siomycin A: Completion of the Total Synthesis

The total synthesis of siomycin A ( 1 ), a representative compound of the thiostrepton family of peptide antibiotics, was achieved by incorporating the five synthetic segments A ( 2 ), B ( 3 ), C ( 4 ), D ( 5 ), and E ( 6 ). The dehydropiperidine segment A ( 2 ) was esterified with the dihydroquinoline segment C ( 4 ), and the subsequent coupling with the β‐phenylselenoalanine dipeptide segment D ( 5 ) at the segment C portion followed by lactamization between the segments A and D gave segment A‐C‐D ( 27 ). This was amidated with the pentapeptide segment B ( 3 ) at the segment A portion followed by one‐pot cyclization (between segments A and B) and elongation (with the β‐phenylselenoalanine dipeptide segment E ( 6 ) at the segment A portion), thus furnishing siomycin A ( 1 ).     

A Formal Total Synthesis of (-)-Brevisamide

A formal total synthesis of (−)-brevisamide has been achieved. The synthetic approach highlights a chemoselective asymmetric dihydroxylation and a one-pot Fraser-Reid epoxidation/PMB protection reaction sequence.     

Formal Total Synthesis of (+)‐Cortistatins A and J

An efficient formal total synthesis of (+) cortistatins A and J has been accomplished, by exploiting a highly diastereoselective intramolecular [4+3] cycloaddition of epoxy enolsilanes as the key reaction to construct rings B and C of the cortistatins in one step.     

Formal Total Synthesis of Platencin

The right bicycle : A concise formal synthesis of platencin was based on an efficient oxygen‐mediated palladium‐catalyzed cycloalkenylation of 1 to form a bicyclo[3.2.1]octane, and a deoxygenative rearrangement of tosylhydrazone 2 to construct the bicyclo[2.2.2]octane 3 . The total yield of the core structure 4 of platencin was 17.5 % for 13 steps from a commercially available compound. Ts=p‐toluenesulfonyl, TBS=tert‐butyldimethylsilyl, Piv=pivaloyl.