A Novel Approach to Synthesis of Tricyclic Diterpenoid

A novel approach has been found and the first total synthesis of (±)-Salvirecognine was accomplished by using it. In which intramolecular cyclization and Friedel-Crafts alkylation took place simultaneously to afford key intermediates for synthesis of aromatic tricyclic diterpenoids OMe PPA O O O OMe 1 2 Scheme 1 As shown in Scheme 1 intramolecular cyclization and Friedel-Crafts alkylation took place simultaneously when compound 1 was treated by PPA at 125 ℃. In which the i-pr…     

Unexpected Novel Rearrangement Reaction: Synthesis of Benzo‐Medium‐Ring Anhydride

When we attempted to synthesize (E)‐3‐(benzo[d][1,3]dioxol‐5‐ylmethylene)‐4‐(propan‐2‐ylidene)‐dihydrofuran‐2,5‐dione, we found a novel rearrangement and obtained the unexpected compound that is assigned as benzo‐medium‐ring anhydride instead of the expected compound. We described the novel rearrangement and a potential method for the synthesis of benzo‐medium‐ring anhydride derivatives.     

A Novel Approach to Synthesis of α，β－Unsaturated Ketones

A new approach to the synthesis of α，β-unsaturated ketones from 1,2,3-trimethyl benzimidazolium salt via the condensation reaction with aldehydes followed by the addition reaction of Grignard reagents with quaternary C=N bond was provided.     

Acid‐Promoted Ring Opening of α‐Hydroxyl Cyclobutanones: A Novel and Facile One‐Pot Synthesis of Nitrile Derivatives

A facile one‐pot synthesis of nitriles via a ring‐opening reaction of cyclobutanone adducts with hydroxylamine hydrochloride was developed.     

Novel Approach to 3‐Methyl‐1H‐quinoxalin‐2‐ones

A novel approach to the synthesis of 3‐methyl‐1H‐quinoxalin‐2‐ones has been described. These compounds were regioselectively prepared by starting from substituted phenylamines and α‐chloropropionyl chloride through the efficient procedures of acylation, nitration, reduction, intramolecular alkylation, and oxidation.     

A New Synthesis of 5,8‐Dimethyl‐2‐tetralone—A Potential Intermediate for the Synthesis of Ring‐A Aromatic Sesquiterpenes. Novel Transformation During Acetoxylation of 5,8‐Dimethyldihydronapthalene

Abstract

An efficient synthesis of 5,8‐dimethyl‐2‐tetralone 4 starting from 5,8‐dimethyl‐1‐tetralone 2 is described. It was converted into the unsaturated derivative 3, which on epoxidation followed by acid hydrolysis yielded tetralone 4. Acetoxylation of 3 with manganese(III) acetate and potassium bromide afforded dimethylnaphthalene 8 and derivative 9.     

Novel Ibuprofen‐based Polyurethane: A New Approach for Drug Delivery

Facile synthesis of novel ibuprofen bearing polyurethane 1 has been achieved for the first time and found to display the release pattern of ibuprofen based on the easy cleavage of ester linkages. Thorough characterizations (FT‐IR, UV‐Vis, NMR, and elemental analysis) were performed to ascertain the structure of polyurethane 1.     

A Novel Stereoselective Total Synthesis of (+)‐5‐epi‐Cytoxazone

Abstract

Stereoselective synthesis of a potent cytokine modulator cytoxazone isomer has been achieved from 2,3‐O‐isopropylidene D‐glyceraldehyde involving Grignard reaction, subsequent formation of an azide followed by reduction to the aminodiol, and finally cyclization of the N‐Boc diol.     

A Novel Approach to the Prediction of Transmembrane Proteins

A novel method based on continuous, wavelet transform (CWT) for predicting the number and location of helices in membrane proteins is presented. The PDB code of lyst is chosen as an example to describe the prediction of transmembrane helices (HTM) by using CWT. The results indicate that CWT is a promising approach for the prediction of HTM.     

Synthesis of 4‐Methyl Pyrrolo[2,3‐b]xanthone,a Novel Ring System

A short, high yielding synthesis of a novel substituted pyrrolo[2,3-b]xanthone has been developed. The synthesis begins with a copper catalyzed Ullmann coupling reaction followed by and intramolecular Friedel-Crafts acylation reaction to establish the xanthone core structure. After a regioselective nitration, a Leimgruber-Batcho synthesis establishes the final pyrrole ring.     

A Short Synthesis of γ-Lactams Via the Spontaneous Ring Expansion of β-Lactams

β-Lactams, derived via the cycloaddition of chlorosulfonyl isocyanate to alkenes, undergo thermal rearrangement at room temperature to afford γ-lactams.     

Synthesis of 3,3‐Dimethyl‐4‐chromanones: Improved Procedures Without Ring Opening

A procedure for the 3,3‐dimethylation of 4‐chromanones under basic conditions was improved; the by‐product from chromanone ring opening was isolated and its structure was determined.     

Synthesis of bis‐Phenylalanine,A Novel Eight‐Membered Cyclic Dipeptide

Cyclic eight‐membered ring lactams have been prepared which are formally analogs of Phe‐Ala or Ala‐Phe dipeptides joined together on their side chains. These are termed bis‐phenylalanines because they are phenylalanine with respect to both of the residues in which the phenyl ring is shared between the two. The key synthetic step was the Negishi coupling of Boc‐β‐I‐Ala methyl ester with a suitably protected 2′‐I phenylalanine.     

A Concise Approach to the Synthesis of L-and D-Deoxyribose

2 Ｄｅｏｘｙ Ｄ ｒｉｂｏｓｅ (1) ,ｔｈｅｓｕｇａｒｐａｒｔｏｆＤＮＡ ,ｉｓｏｎｅｏｆｔｈｅｍｏｓｔｉｍｐｏｒｔａｎｔｓｔａｒｔｉｎｇｍａｔｅｒｉａｌｎｏｔｏｎｌｙｆｏｒｔｈｅｐｒｅｐａｒａｔｉｏｎｓｏｆｎｕｃｌｅｏｓｉｄｅｓ ,ｎｕｃｌｅｏｔｉｄｅｓ ,ＤＮＡａｎｄｔｈｅｉｒａｎａｌｏｇｓ,ｂｕｔａｌｓｏｆｏｒｔｈｅｓｙｎｔｈｅｓｅｓｏｆａｎｕｍｂｅｒｏｆｏｔｈｅｒｂｉｏ ａｃｔｉｖｅｃｏｍｐｏｕｎｄｓ .1Ｒｅｃｅｎｔｌｙｉｔｓａｎｔｉｐｏｄｅ 2 ｄｅｏｘｙ Ｌ ｒｉｂｏｓｅ (2 )ｗａｓａｌｓｏａｔｔｒａ…     

A Novel Stereoseletive Approach to (E)-Vinylic Selenides

Vinylicselenidesareimportantintermediatesinorganicsynthesis.andtheirpromisingpotentialcouldbeanticipatedbythecombinationofthespecialreactivityofseleniumandthereactivit}'associatedwithcarbon-carbondoublebond.particularly'the}'areextremely"set'ulinhighlystereoselectiveC-Cbondformationprocess'.Variouspreparationsofthesecompoundshavebeenreported,butmostofthesemethodsinvolvedthedisposalofhighlytoxicselenides,suchasRSeX,RSeSeRandRSeH.Futhermore,manyofthesemethodsarenotstereocontrolledandgivemixt…     

Efficient Approach to 4‐Benzyl‐5,5‐dimethyldihydrofuranones: Total Synthesis of (±_bold;)‐Solafuranone

A six‐step general and very efficient synthesis of 4‐(arylmethyl)‐5,5‐dialkyldihydrofuranones starting from corresponding aryl aldehyde has been developed. Solafuranone, a novel furanone isolated from the Chinese folk medicine Solanum indicum, has been accomplished starting from 2,6‐dimethylbenzaldehyde in six steps in an overall yield of 70%. Contrary to expectations, solafuranone and its analogue failed to exhibit any significant cytotoxicity against A549 (lung adenocarcinoma) and HL60 (leukemia cells) cell lines.     

Enantioselective Synthesis of (R)‐2‐Methylalkanoic Acids: A Convenient Approach to α‐Substituted Chiral Carboxylic Acid Derivatives

Abstract

Racemization‐free deacylation of N‐acylimidazolidine‐2‐ones using lithium hydroperoxide affords the corresponding α‐substituted chiral carboxylic acids in high yield while permitting recovery of the chiral auxiliary.     

α-Arylation and Ring Expansion of Annulated Cyclobutanones: Stereoselective Synthesis of Functionalized Tetralones

α-Arylcyclobutanones display unique reactivity that makes them valuable synthetic intermediates and target molecules. We describe the preparation of α-aryl- and α-heteroarylcyclobutanones through a direct α-arylation reaction. Problematic fragmentations are avoided by the use of LiO^tBu, which promotes a rapid but reversible self-aldol reaction that slowly releases the enolate required for α-arylation. We also demonstrate the ring expansion of α-arylcyclobutanones, a process that is highlighted in the stereoselective synthesis of 1-methoxy coniothyrinone D.     

Novel and Convenient Approach to Synthesis of AZT／d4T H-phosphonates

A convenient, efficient and general method has been developed for synthesis of H-phosphonate mono and diesters of AZT and d4T through one-pot reaction of phosphonic acid with AZT or d4T and different alcohols using pivaloyl chloride as condensing agent under mild conditions.     

Intramolecular Amidation: Synthesis of Novel Thiazole‐Fused Diazepinones

A new class of thiazole‐fused diazepinones has been synthesized by the application of intramolecular hydrazonolysis, wherein 2‐arylamino‐4‐coumarinyl‐5‐formyl thiazoles were treated with hydrazine hydrate in refluxing ethanol to yield the rearranged products via an interesting ring‐opening and cyclization process.