Synthesis of(+)-(2S, 6S)-trans-α-Irone and of(-)-(2S, 6S)-trans-γ-Irone

A 3:1 mixture of (+)-(2S, 6S)-trans-α-irone ((+)-1) and (?)-(2S, 6S)-trans-γ-irone (?)-2) has been synthesized with ca. 70% e. e. by the ene reaction of (?)-(S)-3 and but-3-yn-2-one.     

Synthesis of N-[2-S -(2-Acetamido-2,3-dideoxy-D-glucopyranose-3-y1)-2-Thio-D-Lactoyl]-L-alanyl-D-isoglutamine

Abstract

N-[2-S-(2-Acetamido-2,3-dideoxy-D-glucopyranose-3-y1)-2-thio-D-lactoyl]-L-alanyl-D-isoglutamine, in which the oxygen atom at C-3 of N-acetylmuramoic acid moiety in N-acetylmuramoyl-L-alanyl-D-isoglutamine (MDP) has been replaced by sulfur, was synthesized from allyl 2-acetamido-2-deoxy-β-D-glucopyranoside (1).

Treatment with sodium acetate of the 3-O-mesylate, derived from 1 by 4,6-O-isopropylidenation and subsequent mesylation, gave allyl 2-acetamido-2-deoxy-4,6-O-isopropylidene-β-D-allopyranoside (4). When treated with potassium thioacetate, the 3-O-mesylate, derived from 4, afforded allyl 2-acetamido-3-S-acetyl-2-deoxy-4,6-0-isopropylidence-β-D-glucopyranoside (6). S-Deacetylation of 6, condensation with 2-L-chloropropanoic acid, and subsequent esterification, gave the 3-s[D-1(methoxycarbonyl)ethyl]-3-thio-glucopyranoside derivative (7). Coupling of the acid, derived from 7, with the methyl ester of L-alanyl-D-isoglutamine, and subsequent hydrolysis, yielded the title compound.     

Synthesis of (E)-5-oxo-2-(3-α and 3β-hydroxy-1-octenyl)-1-(4-N-pyrrolidine-2-butynyl)pyrrolidine

The synthesis of an oxotremorine analog, (E-5-oxo-2-(3α and 3β-hydroxy-1-octenyl)-1-(4-N-pyrrolidino-2-butynyl)pyrrolidine, is reported.     

Synthesis of 2-(α-fluorobenzyl)benzimidazole derivatives

New 2-(α-fluorobenzyl)benzimidazole derivatives have been prepared. Fluorination was carried out from benzylic alcohols using 2-chloro-1,1,2-trifluorotriethylamine reagent. The scope and the rates of formation of the resulting products are dependent on the nature of the substituents. Physical data, ¹H and ¹⁹F NMR chemical shifts of the hydroxy and fluorine compounds are given.     

Synthesis,Crystal Structure,Characterizationand Quantum Chemical Studies on 1N-Acetyl-3-（2,4-dichloro-5-fluorophenyl）-5-（p-methyl-phenyl）-2-pyrazoline

1N-Acetyl-3-（2,4-dichloro-5-fluoro-phenyl）-5-（p-methyl-phenyl）-2-pyrazoline has been synthesized and characterized by elemental analysis, IR, UV-Vis and X-ray single-crystal diffraction. Ab intio calculations have been carded out for the compound by using both B3LYP and HF methods at the 6-31G^＊ basis set. The calculated results show that the predicted geometry can well reproduce the structural parameters. The electronic absorption spectra calculated by B3LYP/6-31G^＊ method are approximate to the experiments and the Natural Bond Orbital （NBO） analyses suggest that the above electronic transitions are mainly assigned to n→π^＊ and π→π^＊ transitions. CIS-HF/6-31G^＊ method is not suitable to predict the electronic spectra for the title compound. The calculation of the second order optical nonlinearity was carded out, giving the value of molecular hyperpolarizability equal to 2.194^＋ 10^-30 esu. On the basis of vibrational analyses, the thermodynamic properties of the compound at different temperature have been calculated, revealing the correlation between C p, m^0, S m^0, H m^0 and temperature.     

Synthesis of propyl O-(α-L-rhamnopyranosyl)-(1→3)-[2,4-di-O-(2s-methylbutyryl)-α-L-rhamnopyranosyl]-(1→2)=(3-O-acetyl-β-D-glucopyranosyl)-(1→2)-βp-D-fucopyranoside,the tetrasaccharide moiety of Tricolorin A

Propyl O-(α-L-rhamnopyranosyl)-(1→3)-[2,4di-O-(2s-methylbutyryl)-α-L-rhamnopyranosyl]-(1→2)-(3-O-acetyl-β-glucopyranosyl)-(1→2)-β-D-fucopyranoside (1), the tetrasaccharide moiety of Ricolorin A, was synthesized in total 23 steps with a longest linear sequence of 10 steps, and overall yield of 3.7% from D-Glucose. The isomerization of the dioxolane-type benzylidene in the prance of NIS/AgOTf was observed. Tetrasaccharide 1 exhibited no activity against the cultured P388 cell as Tricolorin A did.     

Synthesis of poly-β-(α-benzyl-L-aspartate) from L-aspartic β-lactam benzyl ester (3(R)-benzoxycarbonyl-2-azetidinone)

A study on the anionic-assisted polymerization of L-aspartic β-lactam benzyl ester in solution has been carried out in order to prepare an improved poly-β-(α-benzyl-L-aspartate). We have found that both imide formation (with appreciable racemization) and size of the resulting polymers are highly dependent on the nature of reaction medium. A high molecular weight poly-β-aspartate without detectable branching could thus be obtained by using solvents with low polarity. The mechanism of side reactions is discussed.