An Improved Synthesis of dl-Muscone

Muscone.aprincipalodoriferousconshtUent,wasisolatedb3WaIbauminl9O6frOmmuskPodobtainedfromthemalcmuskdeerMo,9cusmoschghnJ'],anditSsthectUret`asdetenninedas(R)-(-)-3-methyl-q'lopentadeCano.eI2l.AnlongnumerousSynthehcmethodsformusconesofarrePOrtedl'-'].theclassicaloneisintramolecularaldolcondensahonof2,l5-hexadecanedjonecamedoutb}'M.Stolllo].However,theshortryntheticschemehasbenhadtwoinherentproblems.ThefirstproblemisagndSynthehcmethodforthedsetone3andthesecondoneisagoodmethodofaldolconde…     

An Improved Synthesis of 2,2′-Dimercaptobiphenyl

The preparation of transition-metal thiolato complexes as synthetic biomimics¹ has led to a resurgent interest in the synthesis of organic thiols and their derivatives. The compound 2,2′-dimercaptobiphenyl, 1, offers interesting possibilities as a ligand, and it has been used recently to displace iron-sulfur clusters from low molecular-weight Fe-S proteins.² The two previous preparations for 1 require a coupling reaction of diazonium salts.^3,4 Overall yields of 10%³ and 30%⁴ are made even less attractive by the need to precipitate copper by-products with H₂S after the coupling step.     

An Improved Synthesis of Inosine 3′-Phosphoramidite

A protocol for the efficient conversion of inosine into its 3′-phosphoramidite synthon for solid phase oligonucleotide synthesis has been developed.     

An Improved Synthesis of Laminin Fragment CR9

Laminin nonapeptide CR9 was synthesized via two different methods.A notably enhanced yicld(46.8%)was obtained from method B compared to that(12.4%)from standard protocol(method A).     

An Improved Synthesis of α-Phenylseleno Arsonium Ylides

The first a-seleno arsonium ylides have been synthesized by Typical procedure for the synthesis of compound sa. To a stirred suspension ofmethoxycarbonylmethylene triphenylarsorane (4a) (0.378 g, I mmol) and triethylamine(0. I I g, 1. 1 mmol) in MeOH-Et,O (0.6 mml, v/v=l f I ) was added dropwise the solutionof phenylselenenyl iodide 2 (0.85 mmol) in MeOH-Et,O (2.8 mml, v/v=l f l) at 0 "C for14 hrs. The mixture was stirred again for 6 hrs. After the solvent in the mixture wasevaporated un…     

An Improved Synthesis of Retinoic Acid from β-Ionone

A convenient and large-scale preparation of retinoic acid 1 from β-ionone in five steps with 38% overall yield is described.The key steps are the epoxidization of 2 with a new methylated agent and the condensation 4 with tetraethyl methylenediphophonate in one-pot procedure to prepare 6.     

An Improved and Convenient Procedure for the Synthesis of Ozagrel

Ozagrel 1 is a 1-alkylimidazole derivative that acts as a selective inhibitor ofthromboxane A2 (TXA2) with an IC50 of 11mol/L. The beneficial effects of TXA2inhibition by ozagrel include improved motor coordination after experimental stroke, andantihypert…     

An Improved Synthesis of α,β Methylenic Cyclic Ketones

This communication describes a convenient two steps procedure for the preparation of α,β methylenic cyclic ketones from arylmethyl ketones involving a preformed Mannich reagent.     

An Improved Synthesis of 10β-Methyl-7α-isopropenyl-5β-hydroxy-3-decalone

An improved synthesis of the title compound using tetramethylammonium hydroxide as catalyst is described.     

An Improved Synthesis of (±)Frullanolide. Application of Selenium Reagents

A new approach to the total synthesis of (±)Frullanolide (1), employing selenium reagents, is described. This methodology has significant advantages over our previously reported synthesis in that (a) the construction of the α-methylene-γ-lactone moiety is made in such a manner to avoid the formation of undesirable stereo- and regioisomers; (b) the synthesis was performed in 7 steps, starting from known octalone 2, with an overall yield of 27%.     

An Improved Method for the Synthesis of Optically Active Tomoxetines and Fluoxetines

A chemoenzymatic approach was applied to the preparation of chiral 3-hydroxy-3-arylpropionates and 3-hydroxy-4,4,4-trifluombutanoate that are potential precursors for certain chiral pharmaceuticals including chiral tomoxetines and fluoxetines.     

Improved Synthesis of Icaritin and Total Synthesis of β-Anhydroicaritin

Natural products icaritin and β-anhydroicaritin with P-glycoprotein(P-gp) inhibitory activities were ciently synthesized in nine steps from commercially available phloroglucinol. A modified Algar-Flynn-Oyamada cyclization and relay Claisen-Cope rearrangement were employed in this concise route. Oiir synthesis offers opportunities to synthesize various icariin analogues for biological and pharmacological investigations.     

An Improved Preparation of 2,5-Dimethoxy-tetrahydrofuran

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An Improved Synthetic Method of Saquinavir

IntroductionThe human immunodeficiency virus(HIV)is thecausative agent of acquired immunodeficiency syndrome(AIDS).Since HIV protease is essential for the repli-cation and maturation of HIV,the inactivation of HIVprotease by either mutation or chemical in…     

Communication: An Improved Synthesis of Methyl 2,3-Anhydro-α and β-D-Lyxofuranosides

Methyl 2,3-anhydro-α (6) and β (7)-D-lyxofuranosides are important intermediates in the synthesis of C-3 substituted derivatives of D-arabinose which show biological activity as a tumor inhibitor.^1,2 Some syntheses of 6 and 7 are reported but they are either expensive or give poor yields ^3-4 and generally the authors refer to Baker and coll.⁵ who synthesized both α and β epoxides from D-xylose in five steps; yields were 28% and 22% respectively. This synthesis is very well described but reaction times and workups are long and several intermediates are distilled with difficulty under reduced pressure. Unger and coll.⁶, using Baker's method, improved the yield of compound 6 and Martin and coll.⁷ described a three steps synthesis of 6 but the final purification is very difficult and the use of mercuric reagents is not consistent with biological activity; furthermore these two publications concern only α anomer 6.     

An Efficient and Stereoselective Synthesis of (+)-α-Cyperone

An efficient and stereoselective three step synthesis of (+)-α-cyperone 1 is described. The key step involves an stereoselective Michael addition of chiral imine to (R)-dihydrocarvone.     

An Improved Synthesis of 2′-Hydroxy-3′,4′,6′-trimethoxyacylophenones

A wide variety of 2′-hydroxypolymethoxyacetophenones and propiophenones, e.g. 1a and 1b are used in the synthesis of flavone and ehromone natural products.¹ Repeated attempts to prepare 1a and 1b by reacting 1,2,3,5-tetramethoxybenzene 2 with acetyl or propionyl chlorides and AlCl₃ in ether² gave products which were difficult to purify.³ We traced the problem to ring-ethoxy contaminants which were isolated and tentatively identified as 3a and 3b.     

Synthesis of (−)-α-CIS-Bergamotene. An Efficient Prenylation Procedure

The introduction of the “isoprene unit” is an important key step in terpene synthesis and to this end, several basic routes employing organometallics have been utilised.     

An Improved Synthesis of β-Nicotyrine from the Dehydrogenation of Nicotine: Comparison of Conventional and Microwave-Assisted Reactions

Abstract

β-Nicotyrine, a minor tobacco alkaloid, can be rapidly prepared in good yield from the dehydrogenation of S-(-)-nicotine over MnO₂ with microwave irradiation. This method is superior to dehydrogenation reactions that utilize S-(-)-nicotine and MnO₂ in a variety of solvents under reflux.     

An Improved Total Synthesis of (±) - Podocarpic Acid by a Cyclialkylation Route

A number of total syntheses of (±) - podocarpic acid (i) have been described¹ King, King and Topliss² first identified one of the products from nonstereo-selective cyclization of (4) with polyphosphoric acid as (±)- ethyl-O-methylpodocarpate (2) and correlated that with the corresponding acid (3), prepared in an extremly poor yield (ca 0.4%)³ by Bhattacharyya³, and Haworth and Moore⁴ by cyclization of (5) with a mixture of sulfuric acid and acetic acid. More recently Mancini, Fringuelli and Taticchi⁵ prepared (3) (in 4.8% yield) by repeating Howorth¹ s cyclization of (4). In continuation of our studies on cyclialky-