A New Stereoselective Total Synthesis of Phomonol

A stereoselective total synthesis of phomonol, following organocatalytic enantioselective epoxidation and intramolecular oxa‐Michael reaction as key steps, is described. The use of readily available D ‐tartaric acid as a chiral source renders this approach quite simple and attractive.     

Synthesis and Coordination Chemistry of Novel Phosphiranes

Abstract

Three-membered PC₂ heterocycles may find interesting applications in tansition metal catalysis but are intrinsically unstaMelll. We developed an efficient simple synthesis of a tricydic phosphirane 3 (BABAR-Phos) which is indefinitely stable in substance at room temperature and may be handled on air (Scheme 1).     

The Ene-Reaction of Phosphaalkynes-Application for the Synthesis of Phosphiranes

Abstract

1,3-Butadienes 1 and 6-Methyl-2H-pyran-2-ones 6 react with two equivalents of phosphaalkynes 2 in a domino-reaction to the diphosphiranes 5 and 9 respectively. Diels-Alder-reaction of 1 with 2 leads to 3 which cannot be isolated. An Ene-reaction of the phosphacyclohexa-1,4-diene 3 with additional 2 gives 4 followed by an intramolecular Diels-Alder-reaction yielding the stable diphosphatricyclooctenes 5.     

New Stereoselective Synthesis of 4-Butyl-α-agarofuran

A potent anxiolytic 4-butyl-α-agarofuran (AF-5) was synthesized from ( )dihydrocarvone. Acid catalyzed hydration of ( )dihydrocarvone and interconversion with β-O-ketone 8 and the key intermediate α,β-unsaturated ketone 5 made this synthesis more practical.     

Very Stable Phosphiranes

Zero-valent platinum complexes as precursors for hydrosilylation catalysts have been prepared for the first time with the new BABAR-Phos ligands (the structure of one such complex is depicted). These rather stable phosphiranes can be obtained when the three-membered PC₂ ring is incorporated into a polycyclic cage.     

A Highly Stereoselective Synthesis of Tetrahydrofurans

The development of a direct and highly stereoselective synthesis of 2,3,5‐substituted tetrahydrofurans has been accomplished through a combination of batch‐ and microchip‐MS‐experiments. This sequential transformation comprises a Lewis acid‐mediated reaction of bis(silyl) dienediolate 1 and a broad range of aldehydes, furnishing products with three new σ‐bonds and three stereogenic centers in a one‐pot process with typically good yields and excellent stereoselectivity. Key steps which have been elucidated primarily with microchip‐MS‐experiments include a vinylogous aldol reaction and a Prins‐type cyclization. Furthermore, a titanium BINOL complex is a powerful chiral catalyst for this process. The products were further converted into bi‐ and tricylic products by carbonyl–ene reactions, proceeding with excellent yields and diastereoselectivity.     

A Stereoselective Total Synthesis of Verbalactone

A stereoselective total synthesis of verbalactone has been achieved starting from commercially available hexanal. The sequence involves Maruoka allylation, diastereoselective iodine‐induced electrophillic cyclization, ring opening of epoxide, and Yamaguchi macrolactonization as the key steps.     

Stereoselective Total Synthesis of Passifloricin A

The stereoselective total synthesis of passifloricin A ( 1 ), a naturally occurring dihydropyranone with leishmanicidal and antiprotozoal activities, has been accomplished starting from protected glyceraldehyde using Maruoka asymmetric allylation, diastereoselective iodo‐carbonate cyclization, and Grubbs' olefin metathesis reactions as the key steps.     

A New Stereoselective Synthesis of Acitretin (=Soriatane®, Neotigason®)

A new synthesis of acitretin via a C₁₅+C₅ route is reported. The C₁₅ unit is the key step, involving a procedure that provides the required (all‐E)‐C₁₅‐aldehyde with high stereoselectivity.     

A New Efficient and Stereoselective Synthesis of 1,3E,5Z-Undecatriene

1,3E,5Z-Undecatriene is synthesized by coupling of Z-heptenyl copper reagent, obtained through carbocupration of acetylene, with 1-chloro-1E,3-butadiene, in the presence of 5% NiCl₂(PPh₃)₂     

Synthesis of New 4-Thiazolidinylphosphonates via Stereoselective Pudovik Reaction

Diastereomeric pure phosphite anions 2 adds to the C=N bond of 3-thiazolines 3 to give the corresponding derivatives 4 of the pharmacological active 4-thiazolidinylphosphonates 1 via Pudovik reaction.     

A Stereoselective Total Synthesis of Decarestrictine I

A convergent and stereoselective total synthesis of decarestrictine I, a polyketide natural product, is described. Both acid and alcohol fragments were prepared from the readily available L ‐malic acid via Still? Gennari olefination and Sharpless asymmetric epoxidation. The Steglich esterification and ring‐closing metathesis (RCM) are employed to combine both acid and alcohol fragments.     

A Simple Stereoselective Synthesis of Aplysinopsin Analogs

Simple and stereoselective syntheses of aplysinopsins and their analogs from either methyl 2‐[(2,2‐disubstituted ethenyl)amino]‐3‐(dimethylamino)prop‐2‐enoates 11 or 5‐[(dimethylamino)methylidene]imidazolidine‐2,4‐diones 20 are described. The structures of products are established by ¹H‐ and ¹³C‐NMR, and NOESY spectroscopy, and X‐ray crystal‐structure analysis.     

L-苏式二氢鞘氨醇的立体选择性合成

二氢鞘氨醇（ＤＨＳ）是２－氨基－１，３－二羟基的饱和长链氨基醇化合物，是构成鞘脂类（包括鞘磷脂和糖鞘脂）的主链部分．由于鞘脂类在自然界中来源稀少，又很难得到纯品．因此，作为鞘脂类主链部分的二氢鞘氨醇的合成有重要的意义［１］．二氢鞘氨醇有两个手性碳，共...     

A Short and Highly Stereoselective Synthesis of Cerebrosterol

Ｃｅｒｅｂｒｏｓｔｅｒｏｌ (2 4Ｓ ｈｙｄｒｏｘｙｃｈｏｌｅｓｔｅｒｏｌ,1)ｆｏｒｍｅｄｉｎｓｍａｌｌａｍｏｕｎｔｓｉｎｈｕｍａｎａｎｄａｎｉｍａｌｂｒａｉｎ1ｆｒｏｍｃｈｏｌｅｓ ｔｅｒｏｌｉｓｉｍｐｏｒｔａｎｔｆｏｒｃｈｏｌｅｓｔｅｒｏｌｈｏｍｅｏｓｔａｓｉｓｉｎｔｈｉｓｏｒｇａｎ .Ｔｈｅｅｘｃｅｓｓｃｈｏｌｅｓｔｅｒｏｌｉｓｃｏｎｖｅｒｔｅｄｉｎｔｏ 2 4Ｓ ｈｙｄｒｏｘｙ ｃｈｏｌｅｓｔｅｒｏｌｂｙａｕｎｉｑｕｅｂｒａｉｎ ｓｐｅｃｉｆｉｃ 2 4Ｓ ｈｙｄｒｏｘｙｌａｓｅ ,ｗｈｉｃｈｃｏｕｌｄｂｅｒ…     

Stereoselective Total Synthesis of Goniothalesdiol A via Chiron Approach

The stereocontrolled synthesis of goniothalesdiol A, a dihydroxylated tetrahydropyran compound, has been accomplished using D ‐ribose as chiral precursor. The key steps involved are aryl Grignard reaction, stereoselective alkoxy‐directed keto reduction, and intramolecular oxy‐Michael addition.     

A Stereoselective Synthesis of Pear Ester Via Arsenic Ylide

The paper describes a four-step synthesis of ethyl (2E, 4Z)-2, 4-decadienoate (pear ester) from propargyl alcohol with a 50% total yield. It also gives the synthesis of ethyl (2E, 4E)-2, 4-decadienoate. In both cases arsenic ylides were used to give the satisfactory results.     

A Concise and Stereoselective Synthesis of Cathasterone＇s Side Chain

Introduction Brassinolide (compound 1) and cathasterone (compound 2)(Scheme 1), which is the biosynthetic precursor of compound 1, are a new type of promoting materials for plant growth^[1,2]. Owing to their novel structural features and their remarkable physiological activities, much effort has been made to develop the methods for the synthesis and biosynthesis of compound 1^[3],