Stereoselective total synthesis of racemic grandisol via 3-oximino-1,4,4-trimethylbicyclo[3.2.0]heptane. An improved practical procedure

(±)Grandisol was stereoselectively obtained via 1,4,4-trimethylbicyclo¦3.2.0¦heptane-3-one and its oxime by an improved procedure. 2,5,5-Trimethylhept-1,6-dien-4-ol, the open chain molecule, was synthesized by two routes. Its conversion into ( )grandisol was performed emploing the photobicyclization as key step.     

An improved synthesis of various racemic polyphenolic tetrahydroisoquinoline alkaloids

An improved and straightforward synthesis of (±)-coclaurine (Va), (±)-isococlaurine (Vb), (±)-reticuline (VIIIa) as well as an alternate route to an intermediate in the synthesis of (±)-multifloramine, the (±)-diphenol (VIIIb), is described.     

A facile total synthesis of racemic aklavinonet

A convergent total synthesis of aklavinone, based on the annelation reaction of cyanophthalide addition to an enone as the key step, was accomplished.     

An efficient and convenient approach to the total synthesis of sphingofungin

As a new member of the sphingofungin family, sphingofungin F exhibits interesting physiological activities with a structural unit of an alpha-substituted alanine. Described herein is an efficient and convenient stereoselective synthesis of sphingofungin F from L-(+)-tartaric acid, which utilizes Sharpless asymmetric epoxidation of allylic alcohol and Lewis acid-catalyzed intramolecular epoxide-opening reaction with an N-nucleophile, to introduce the other two desired stereogenic centers. Side chain functionality was incorporated into the chiral segment using a Wittig reaction.     

An improved procedure for the synthesis of 2-morpholinoethanamine

2-Morpholinoethanamine is prepared rapidly mainly in aqueous conditions from inexpensive and commercially accessible starting materials. The process development of an effective synthetic route by utilizing morpholine as the starting material via Michael addition, hydrazinolysis, and Curtius rearrangements was undertaken. The optimal conditions were selected in the experiments. The total yield was 81.8% and it was a convenient process.     

Short eight-steps total synthesis of racemic asteriscunolide C

A concise total synthesis of racemic asteriscunolide C in eight steps has been described starting from neopentane diol involving an efficient Yamaguchi esterification using an aldehyde-acid, intramolecular Horner–Wittig–Emmons olefination, and a late stage ring-closing metathesis to construct the strained 11-membered ring with one Z- and two E-double bonds.     

An improved total synthesis of UDP-N-acetyl-muramic acid

Biochemical testing for novel inhibitors of Mur ligases requires several commercially unavailable and structurally complex substrates. We describe a modified synthetic strategy for the total chemical synthesis of the MurC ligase substrate UDP-N-acetyl-muramic acid which includes several improvements over published methods, especially with regard to purification procedures. The synthetic strategy is applicable for the synthesis of further Mur ligase substrates.     

An improved procedure for the synthesis of 1,1-difluoro-2-hydroxyalkylphosphonates

The reaction of diethyl difluoro(trimethylsilyl)methylphosphonate with arenecarbaldehydes and aryl methyl ketones is effected with the aid of a catalyst. cesium fluoride, at room temperature to afford the title compounds.     

An improved procedure for the synthesis of 4-methylimidazol-2-one

A novel one-pot synthetic method of 4-methylimidazol-2-one is described. The target compound is conveniently synthesized from sodium diformylamide, a modified Gabriel reagent prepared, through condensation, hydrolyzation and cyclization reactions without separating intermediates, its total yield is 75.8%.     

Synthesis of polyprenylated acylphloroglucinols using bridgehead lithiation: the total synthesis of racemic clusianone and a formal synthesis of racemic garsubellin A

The synthesis of polyprenylated phloroglucinol natural products, including clusianone, nemorosone, and garsubellin A, was pursued by a strategy involving construction of a core bicyclo[3.3.1]nonanetrione structure and subsequent elaboration via organolithium intermediates. Appropriate bridged core structures were obtained through the cyclization of a suitably substituted cyclohexanone enol ether or enol silane with malonyl dichloride. Additional substituents were then introduced by means of regioselective lithiation reactions, including the generation of bridgehead enolates, thus enabling the total synthesis of clusianone and also of an advanced intermediate toward nemorosone. In the case of garsubellin A, an additional THF-like ring was elaborated by a biomimetic 5-exo-tet cyclization of an enol ether (or enol) with a side-chain epoxide. This enabled a formal synthesis of racemic garsubellin A by accessing one of the late intermediates in the Danishefsky synthesis.     

Convergent total synthesis of the racemic HIF-1 inhibitor laurenditerpenol

The convergent total synthesis of the HIF-1 inhibitor laurenditerpenol 1a is reported. The key step is the Julia olefination-reduction process between the two components, the sulfone 4 (prepared from the dimethylfuran-maleic anhydride Diels-Alder adduct) and the aldehyde 3 (prepared from 3-methylcyclohexenone).     

An improved procedure for the preparation of β-thiohydroximates for glucosinolate synthesis

A novel and simple method is described for the synthesis of β-thiohydroximates from oximes and 2,3,4,6-tetra-O-acetyl-1-thio-β-d-glucopyranose, which are key intermediates in the synthesis of glucosinolates. The procedure involves the in situ formation of an oximyl chloride from the oxime, using inexpensive bleach, which is then reacted directly under basic conditions with the thioglucopyranose.     

A convenient procedure for the synthesis of fused fluoro isoquinolines

A base-promoted conversion of ortho-trifluoromethyl benzyl derivatives of NH-heterocycles into a respective fluorinated isoquinolines (38-57% isolated yields) is reported. The reaction is general for the benzylated derivatives of the electron-rich NH-heterocycles and the respective derivatives of pyrazole. The outcome of the reaction could be explained by an intermediate formation of a highly reactive quinone methide species.     

An improved procedure for the synthesis of 2-methoxyisobutylisonitrile: An efficient complexing agent for99mTc

^99mTc hexakis (2-methoxyisobutylisonitrile) is a cationic complex useful as a myocardial perfusion agent. The synthesis of 2-methoxyisobutylisonitrile (MIBI) by a modified and improved procedure in a two-step process with an overall yield of 53% is described. The preparation of its copper and technetium-99m complexes is also presented.     

An improved coupling procedure for the barton‐zard pyrrole synthesis

An improved final step in the Barton‐Zard pyrrole synthesis uses inexpensive potassium carbonate as base in the coupling‐cyclization reaction of vic‐nitro‐acetates with isocyanides. In this modification the isolated yields of synthetically useful 2‐carboalkoxypyrroles ( 1a,b and 3 ) and 2‐(p‐toluenesulfonyl)pyrroles (2a,b) consistently rise to the 78‐89% range. Conversion of 2a to 5‐(p‐toluenesulfonyl)‐2‐pyrrolinone 4 is conveniently and directly achieved by reaction with 30% hydrogen peroxide in acetic acid, thus circumventing the commonly used two step procedure involving bromination followed by solvolysis.     

An improved procedure for the synthesis of benzimidazoles,using palladium-catalyzed aryl-amination chemistry

New, improved conditions have been developed and optimized for the synthesis of benzimidazoles by intramolecular palladium-catalyzed aryl-amination chemistry. This methodology, combined with a "catch and release" purification strategy, has led to a range of these heterocycles being prepared rapidly and in excellent yield.