A new synthetic route to 3-polyfluoroalkyl-containing pyrroles

A novel approach to 3-polyfluoroalkyl pyrroles is reported based on step by step reactions: 1,2-addition of Me₃SiCN to β-alkoxyvinyl polyfluoroalkyl ketones, reduction with LiAlH₄ and subsequent hydrolysis with intramolecular cyclization. The hydrolytic instability of various polyfluoroalkyl groups at position 3 of the pyrrole ring was evident and a pathway for the hydrolysis was proposed.     

A pinacol rearrangement/oxidation synthetic route to hydroxyphenstatin

In an attempt to develop biologically active compounds from the inactive trans isomer (3a) of stilbene 1a, after asymmetric dihydroxylation to optically pure (R,R)-diol 8 the unexpected racemic diphenylacetaldehyde (9) was generated via a Pinacol rearrangement. Several derivatives of diphenylacetaldehyde 9 were synthesized (11-15) and reported. Further reaction of aldehyde 9 during desilylation through autoxidative decarbonylation afforded benzophenone 2b, designated hydroxyphenstatin, a potent antitumor and antimitotic agent. Hydroxyphenstatin showed potent inhibition of the tubulin assembly (IC(50) 0.82 microM) and exhibited an ED(50) of 2.5 microg/mL against the P388 lymphocytic leukemia cell line.     

A novel synthetic route to 2-halo-3,4-dicyanopyridines

2-Bromo-3,4-dicyanopyridine 2 was obtained in moderate yield by reacting 1,1,2,2-tetracyano-3-trimethylsiloxycyclobutane 1 with phosphorus tribromide. Similarly, reaction of 1 with chlorinating reagents such as thionyl chloride and oxalyl chloride led to the corresponding 2-chloro-3,4-dicyanopyridine 3 in 40% yield. A reaction mechanism is suggested.     

Blends of natural and synthetic polymers: A new route to novel biomaterials

Blends of natural and synthetic polymers were studied for potential applications in the biomedical field. Collagen and hyaluronic acid were mixed in aqueous solution with poly(vinyl alcohol) and poly(acrylic acid). The properties of the blends were studied by differential scanning calorimetry and dynamic mechanical thermal analysis. Some methods were also investigated to enhance the miscibility of the polymers in these blends.     

A simple and efficient route to β-substituted pyrroles

$\text{N}$-Phenylsulfonylpyrrole undergoes Friedel-Crafts acylation exclusively at the β-position of the pyrrole ring, thus allowing a simple and efficient synthesis of β-acylated pyrroles.     

A novel synthetic route to 7-MAC from 7-ACA

An efficient and practical seven-step procedure is described for the synthesis of (6R,7S)-benzhydryl-7-amino-7-methoxy-3-((1-methyl-1H-tetrazol-5-ylthio)methyl)-8-oxo-5-thia-1-aza-bicyclo [4.2.0]oct-2-ene-2-carboxylate (7-MAC, 3) with overall yield of 49 %. This synthesis features a convenient and highly selective method for the introduction of 7α-methoxy group to cephalosporin nucleus in 10 using MeOLi/t-BuOCl in THF.     

New synthetic route to 9,10-imino-phenanthrene

The synthesis of 9,10-imino-phenanthrene is performed in two steps from phenanthrene. N-alkylation using Michael type reaction is also disclosed.     

A novel synthetic route to fused propenochlorin and benzochlorin photodynamic therapy probes

Reaction of meso-(2-formylvinyl)octaethylporphyrin with (CH3)3SiCN-Cu(OTf)2 produced unexpected 10(3)-trimethylsiloxyl and 10(3)-hydroxyl fused propenochlorins which, in H2SO4, underwent subsequent migration of the 8-ethyl group to the 10(3)-position of the exocyclic benzene ring to form a novel benzochlorin.     

A novel synthetic route to substituted pyranoanthocyanins with unique colour properties

Anthocyanins, isolated from natural sources by countercurrent chromatography, were reacted with cinnamic acids bearing at least one electron-donating substituent at the para-position. The resulting pyranoanthocyanins obtained by this simple one-step reaction were much less susceptible to pH shifts and retained their original colour over a wide pH-range. Through reaction with p-dimethylamino cinnamic acid, synthetic malvidin- and cyanidin-based anthocyanins with a unique violet hue were prepared.     

Selenosulfonation of allenes and subsequent rearrangement of the adducts: A facile synthetic route to β-arylsulfonyl-substituted allylic alcohols

$\text{Se}$-Phenyl areneselenosulfonates add readily to allenes in a highly regiospecific fashion (eq 3) to give $\text{5}$. Oxidation of the PhSe group in $\text{5}$ to PhSe(O) is followed by [2,3]-sigmatropic rearrangement to $\text{6}$ and hydrolysis of $\text{6}$ to the β-arylsulfonyl-substituted allylic alcohol $\text{7}$, thereby providing a simple, high-yield route to these interesting compounds.     

A synthetic route to thionolactones

The treatment of O-alkyllactonium tetrafluoroborate salts with anh. NaSH in CH₃CN at 0°C led to five-, six-, and seven-membered thionolactones (44– 90% yield).     

New synthetic route to substituted dihydroazulene photoswitches

A new procedure for functionalization of the dihydroazulene photoswitch on its seven-membered ring was developed, which has allowed isolation of the first dihydroazulene with a phenyl substituent at position 5 from a mixture of regioisomers. Light-induced ring-opening to the corresponding vinylheptafulvene and the thermal back-reaction was studied in detail.     

The rearrangement of cyclopropylketone arylhydrazones. Synthesis of tryptamines and tetrahydropyridazines

The cyclopropyliminium rearrangement of cyclopropylketone arylhydrazones may result in two possible products. The first one forms via cyclopropane ring-opening and ring-closure to give six-membered tetrahydropyridazines. The second is formed via ring-closure resulting in a five-membered ring and subsequent Grandberg rearrangement into a tryptamine. The product ratio depends on the nature of the starting hydrazones.     

A Claisen rearrangement route to the vineomycins

Anthrarufin is converted by a high yield route involving sequential Claisen rearrangements to an intermediate (3) suitable for the synthesis of vineomycins     

A novel and highly efficient synthetic route to unsymmetrical organoselenides using cesium bases

A new and convenient one-pot method for the preparation of unsymmetrical selenides has been developed. In the presence of cesium hydroxide, molecular sieves, and DMF, benzeneselenol undergoes direct alkylation with various alkyl halides for the synthesis of alkyl phenyl selenides in moderate to excellent yields. Another method to prepare unsymmetrical organoselenides was also completed by coupling terminal alkynes with benzeneselenyl bromide. As an application, the synthesis of a selenopeptide was also accomplished. Furthermore, this methodology was extended to the synthesis of an organoselenide on solid support.     

A novel and simple route for the synthesis of 3,4‐disubstituted pyrroles

A new class of 3,4‐disubstituted pyrroles has been prepared by the reaction of 1‐aroyl‐2‐arylsul‐fonylethenes and 1,2‐diarylsulfonylethenes with tosyl methyl isocyanide.     

A novel synthetic route to 6-oxabicyclo[3.1.1]heptane skeleton

6-Oxabicyclo[3.1.1]heptane skeleton is synthesized starting from bicyclo[2.2.1]heptane skeleton, in which as a key reaction, Baeyer-Villiger oxidation of the tricyclic oxetane (19) is involved.     

Photochemistry of 3,6-dihydro-1,2-oxazines: A versatile route to substituted pyrroles

A high yield pyrrole synthesis which employs a sequence of cyclo-addition, photoextrusion of H₂O and Birch reduction has been developed.     

New synthetic route to granulatimide and its structural analogues

The Stille coupling reaction of stannylindole 12 with 4-iodoimidazole 13 (or 24) in the presence of PdCl(2)(PPh(3))(2) gave the corresponding indole-imidazole coupling product 14 (or 25), thereby affording a new synthetic approach to the alkaloid granulatimide (7), isolated from the Brazilian ascidian Didemnum granulatum, as well as its structural analogues, 10-methylgranulatimide (23), 17-methylgranulatimide (30), 10,17-dimethylgranulatimide (31).