An efficient two-step total synthesis of the quaterpyridine nemertelline

Regioselective and univocal Suzuki cross-coupling reactions performed on halopyridinyl boronic acids provide a flexible and versatile route to a multigram scale synthesis of 2,2'-dichloro-3,4'-bipyridine 14, which allows couplings with excess pyridin-3-yl boronic acid to give a new and efficient two-step rapid synthesis of nemertelline, the quaterpyridine neurotoxin isolated from a Hoplonemertine sea worm.     

Highly efficient two-step synthesis of C-sp3-centered geminal diiodides

[reaction: see text] Trisubstituted gem-diiodoalkenes of functionalized chains are efficiently reduced to the corresponding terminal geminal diiodides in high yields upon treatment with the diazene precursor, diethyl 4-(hydrazinosulfonyl)-benzyl phosphonate.     

Highly efficient two-step selective synthesis of 2,6-dimethylnaphthalene

2,6-Dimethylnaphthalene (2,6-DMN), a key raw material for poly(ethylene naphthalate) (PEN), was selectively synthesized via a two-step process in an overall 66% yield from commercially available 4-bromotoluene and 3-methyl-3-buten-1-ol. The ligand-free Heck reaction of the starting materials produced γ-(p-tolyl)-substituted aldehyde that was cyclized with an acid to give 2,6-DMN after in situ oxidation. No other isomers of 2,6-DMN were found.     

An easy and efficient synthesis of 3-nitrochromans

The reaction of nitro olefins reacted with (E)-(2-hydroxyphenyl)-1-nitroethylene in the presence of DABCO generates 3-nitrochroman with a high stereoselectivity. A possible reaction mechanism for the reaction and the transition states involved in producing the final product are proposed. The treatment of 3-nitrochromans with t-BuOK give alkenes.     

An efficient synthesis of an alphavbeta3 antagonist

A practical preparation of an alpha(v)beta(3) antagonist is reported. The antagonist consists of three key components, a tetrahydronaphthyridine moiety, a beta-alanine moiety, and a central imidazolidone moiety. The tetrahydronaphthyridine component was prepared using two different methods, both of which relied on variations of the Friedl?nder reaction to establish the desired regiochemistry. The beta-alanine component was prepared using Davies' asymmetric 1,4-addition methodology as the key stereo-defining step. The central imidazolidone portion was created from these two components using an effective three-step cyclization protocol. Thus, a highly convergent process for the drug candidate was defined.     

An efficient synthesis of diethyl coumarin-3-phosphonates

A general synthesis of a number of diethyl coumarin-3-phosphonates (3) has been achieved using titanium tetrachloride-pyridine as the condensing agent.     

An efficient one-pot, two-step synthesis of 4-substituted 1-heteroarylpiperazines under microwave irradiation conditions

A highly efficient one-pot, two-step microwave procedure has been developed for the synthesis of 4-substituted 1-heteroarylpiperazines. Microwave heating of heteroaryl chlorides with 1,4-diazabicyclo[2.2.2]octane (DABCO) at 160 °C for 15 min yielded 1-heteroaryl-4-(2-chloroethyl)piperazines, which could be further reacted with various nucleophiles, again under microwave irradiation conditions, to give an array of 4-substituted 1-heteroarylpiperazines in good to excellent yields.     

A two-step sulfurization for efficient solution-phase synthesis of phosphorothioate oligonucleotides

A solution-phase approach for the synthesis of phosphorothioate oligonucleotides that circumvents the use of chromatographic purifications of protected phosphorothioate intermediates was developed. Implementation of a two-step sulfurization protocol in the phosphoramidite method allows efficient isolation of the intermediate phosphorothioates by extractions. The viability of this approach is demonstrated by the synthesis of a hexameric phosphorothioate oligonucleotide fragment.     

An efficient synthesis of 3-substituted 3H-pyrimidin-4-ones

[reaction: see text] A novel and practical synthesis of 3-substituted 3H-pyrimidin-4-ones is described. The key step involves the cyclization of enamide esters, derived from readily available beta-keto esters, with trimethylaluminum and various primary amines.     

An easy two-step synthesis of 1-imidazolylmethyl esters

A new synthesis of 1-imidazolylmethyl esters is described starting from the appropriate carboxylic acids via imidazolide intermediates.     

An unexpected and efficient synthesis of 3-chloro-4-cyanopyridine

Reaction of 4-cyanopyridine N-oxide with phosphorus oxychloride/phosphorus pentachloride gave 3-chloro-4-cyanopyridine in good yield in sharp contrast to the expected chlorination in the 2-position. A mechanistic interpretation of the results is proposed involving a chloride attack at the 4-position as the main feature.     

An efficient synthesis of optically active 3-amino-3-alkyl-2-oxetanones

An efficient two-step synthesis of p-toluenesulfonic acid salts of optically active 3-amino-3-alkyl-2-oxetanones is reported that involves cyclization of N-Boc-α-alkylserines under Mitsunobu reaction conditions followed by deprotection of the amino group with trifluoroacetic acid in the presence of anhydrous p-toluenesulfonic acid.     

An efficient synthesis of Ecopladib

An efficient synthesis of Ecopladib, an indole inhibitor of cytosolic phospholipase A₂α, is described. A new reaction involving indole C3 reductive alkylation using an acetal in the absence of water and a novel transformation of the C2 methyl to an aldehyde via dimethyl sulfoxide-mediated oxygen-transfer reaction are used in the present synthesis, which dramatically increased the synthetic efficiency.     

An efficient synthesis of sulfamides

Here we report an efficient synthesis of sulfamides. 3,5-Lutidine was found to be an optimal solvent and catalyst for the reaction. The method was developed during our efforts to synthesize a series of novel FKBP-12 inhibitors in which the known ketoamide linker was replaced with sulfamide.     

An efficient synthesis of oosporein

Fungal metabolite oosporein was prepared in four steps and 24% overall yield starting from 2,5-dimethoxytoluene. It was demonstrated that treatment of phoenicin with pyrrolidine and copper(II) acetate led to oosporein, whereas similar treatment of the isomeric ‘isophoenicin’ produced a benzofuran diquinone. No chromatography was required during any step of the synthesis.     

An efficient synthesis of futalosine

Futalosine is a naturally occurring nucleoside comprised of an inosine core with a 3-carboxyphenyl methylene ketone functionality replacing the C-5′ hydroxyl. Recent studies have shown that it is a key intermediate in an alternative biosynthetic pathway that generates menaquinone in a variety of bacterial species. Here we report the first synthesis of futalosine in seven steps from inosine in an overall 17% yield. This work will enable further studies on menaquinone biosynthesis in pathogenic bacteria.     

An efficient synthesis of N-tert-butoxycarbonyl-O-cyclohexyl-L-tyrosine

A facile and efficient synthesis of N-tert-butoxycarbonyl-O-cyclohexyl-L-tyrosine [Boc-Tyr(Chx)-OH] is described. Boc-Tyr-OH was treated with NaH in dimethylformamide and then with 3-bromocyclohexene to give N-Boc-O-(cyclohex-2-enyl)-L-tyrosine [Boc-Tyr(Che)-OH] in 70% yield. Hydrogenation of Boc-Tyr(Che)-OH over PtO2 afforded Boc-Tyr(Chx)-OH in almost quantitative yield. The highest yield was achieved when a side product in the synthesis of Boc-Tyr-OH, Boc-Tyr(Boc)-OH, was not removed, because it was also converted to Boc-Tyr(Che)-OH without any additional manipulations. The new synthetic method described here is convenient for practical use, and would facilitate the widespread use of the Chx group for the hydroxy-protection of Tyr.