Chemo- and regioselective modification of l-histidine with tertiary cyanopropargylic alcohols

l-Histidine chemo- and regioselectively reacts with tertiary cyanopropargylic alcohols (4,4-di-alkyl-4-hydroxybut-2-ynenitriles) under mild conditions (water, 6.4 wt.% NaOH, 5—15 °C, 72—175 h) with the formation of new “unnatural” amino acids containing an iminodihydrofuran substituent in the amino group (50—70% yields).     

Synthesis and conformational analysis of furfuryl vinyl ethers

Five furfuryl vinyl ethers were synthesized from the corresponding furfuryl alcohols and acetylene at high and atmospheric pressures in superbasic medium KOH-DMSO. On the example of 2-vinyloxymethylfuran and 2-vinyloxymethyltetrahydrofuran, their conformational structures have been studied by quantum chemistry methods, NMR and IR spectroscopy. In particular, from the results of the quantum-chemical calculations, as well as on the basis of experimental measurement and nonempirical calculations of the high level spin-spin coupling constants ¹³C-¹³C and ¹³C-¹H, a conclusion has been drawn on the s-cis-orientation of the vinyl groups with respect to the C_α-O bond in the predominant conformers of 2-vinyloxymethylfuran and 2-vinyloxymethyltetrahydrofuran.     

L-ProT catalyzed highly regioselective N-alkoxyalkylation of purine rings with vinyl ethers

An efficient and regioselective synthesis of N-9 alkoxyalkylated purine nucleoside derivatives was achieved via the N-alkoxyalkylation of purine rings with vinyl ethers catalyzed by L-ProT.The advantages of this protocol include good to excellent yield,mild reaction condition,and simple manipulation.A plausible mechanism for the transformation was given.     

The reaction of vinyl ethers with acridine

The reaction of vinyl ethers with acridine gives new acridine derivatives in the presence of an organic ammonium salt and alcohol. An organic ammonium salt such as acridinium chloride affect this reaction. All of the addition products were obtained as dihydroacridinyl derivatives. Moreover, in the reaction of ketene silyl acetal with acridine, the addition products were also obtained as the dihydroacridine derivatives.     

Homopolymers and copolymers of vinyl ethers of rosin-derived alcohols

Two vinyl ethers of rosin-derived alcohols were homopolymerized with free-radical and cationic initiators. A polymer was obtained from the vinyl ether of the alcohol from Foral in good conversion by free-radical initiators but it was not a high molecular weight product. Cationic initiators were more effective; boron trifluoride etherate proved to be best. All of the homopolymers were obtained as white powders with high crystallinity. Copolymerizations of the vinyl ethers and vinyl chloride have been studied with the use of free-radical initiators. Cationic-initiated copolymers of the vinyl ethers and isobutyl vinyl ether were studied. Those containing less than 20% of the rosin vinyl ethers were rubbery, of high molecular weight, and could be crosslinked with peroxide.     

Cyclization of vinyl ethers derived from amino alcohols

Cyclization of vinyl ethers derived from linear and cyclic α- and β-amino alcohols, catalyzed by mercury(II) acetate gave 2-methyloxazolidines and 2-methylperhydro-1,3-oxazines in 37–94% yield.     

Reaction of the vinyl ethers of heterocyclic imino alcohols with acyl halides

Conclusions The reaction of the vinyl ethers of heterocyclic imino alcohols with acyl halides gave a number of new vinyl ethers of heterocyclic amido alcohols as 11 mixtures of the isomeric 3,6- and 5,6-dihydropyrans, and ³- and ⁴-piperidines.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2538–2541, November, 1980.     

Reactions of furfuryl alcohols with maleic anhydride

The reactions of some furfuryl alcohols with maleic anhydride have been reinvestigated and, for the first time, conditions defined for the production of intramolecular Diels-Alder adducts. In basic conditions these adducts yield phthalides in high yields.     

Chemo- and regioselective reductive opening of azetidinium ions

Enantiomerically pure azetidinium trifluoromethanesulfonates were opened by various hydride reagents. LiAlH₄ and NaBH₃CN reacted with a complete regioselectivity and the latter reagent also reacted in a chemoselective way, leaving unaffected an ester or a cyano moiety present in the substrate. This reaction provides 1,2-diamines, 1,2- and 1,4-amino alcohols or α-amino esters by combining proper choice of substrate and hydride reagent.     

Stereo- and regioselective formation of silyl enol ethers via oxidation of vinyl anions

Oxidation of E- and Z-vinyl lithiums with silyl peroxides 5 affords silyl enol ethers 3 in good to excellent yield with retention of configuration. This methodology represents a useful new procedure for the stereo- and regioselective synthesis of ketone enolates.     

Condensation of 2- and 4-fluorobenzaldehydes with vinyl ethers derived from amino alcohols

2- and 4-Fluorobenzaldehydes reacted with amino alcohol vinyl ethers to give Schiff bases, oxazolidines, and imidazolidines containing a vinyloxy group. The products attract interest as potential biologically active compounds.     

Chemo- and stereoselectivity in titanium-mediated regioselective ring-opening reaction of epoxides at the more substituted carbon

Chemo- and stereoselectivity in the ring-opening reaction of epoxides with a reagent prepared from allylmagnesium halide and chlorotitanium triphenoxide is described. It has been proven that the allylating reagent can also be used for the reaction of epoxides bearing a tert-butyl ester, amide, or acetal moiety, and that the epoxide cleavage regioselectively takes place at the more substituted carbon in all cases. Interestingly, while the reaction of acyclic 2,2,3-trialkyl epoxides or 3,3-disubstituted 2,3-epoxy alcohol derivatives with the allyltitanium reagent yielded the allylated products as an almost 1:1 diastereomixture, the ring-opening reaction of 2-substituted 2,3-epoxy alcohol derivatives stereospecifically proceeded through the anti pathway. The latter reaction is extremely useful for asymmetric construction of quaternary carbon centers.     

Reactions of alkyl furfuryl ethers and sulfides with n-butyllithium

The direction of the reaction of alkyl furfuryl ethers and sulfides with n-butyllithium is in agreement with the results of basic H-D exchange in the same compounds: In the case of the ethers H-D exchange and metallation take place primarily in the free a position of the furan ring, whereas in the case of the sulfides these reactions take place primarily at the methylene group of the side chain located between the sulfur atom and the furan ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 744–746, June, 1984.     

Electron transfer promoted regioselective ring-opening reaction of cyclopropyl silyl ethers

Oxidative ring-opening reactions of cyclopropyl silyl ethers incorporated into bicyclo[m.1.0]alkane framework were investigated. The results show that the regioselectivities for ring-opening of intermediate radical cations, formed by single electron transfer, are governed by the nature of the nucleophile as well as oxidizing species.     

Catalytic hydroamination of furfuryl and tetrahydrofurfuryl alcohols with nitriles

Reaction of furfuryl and tetrahydrofurfuryl alcohols with nitriles over copper oxide catalysts under a hydrogen pressure of 15 atm at a temperature of 230C gives N-alkylfurfuryl- (yield 46–50%) and N-alkyl-tetrahydrofurfurylamines (49–53%), and N-alkylpiperidines (28–41%). A reaction mechanism is proposed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 23–26, January, 1988.     

Indium-mediated consecutive 1,2-shift reaction and regioselective allylation of vinyl epoxides

Allyl indium, prepared from allyl bromide and indium metal in aprotic solvent, reacts with terminal vinyl epoxides at room temperature to afford various bishomoallyl alcohols in moderate to high yields via consecutive 1,2-shift reaction and regioselective allylation.