Functionalization of the 3β-methyl group of penicillin

A number of penicillins functlonalized at the 3β-methyl position have been syntheslsed. The progenitor of these compounds Is the 3β-hydroxymethyl penicillin 1.     

Biocatalytic Synthesis of Pyruvate from DL-lactate with Enzymes in Pseudomonas sp.

Pyruvate has received increasing attention in recent years as a potential precursor for the synthesis of L-amino acids1. Compared with other small non-chiral building blocks, pyruvate is relatively expensive. Conventional processes for preparing pyruvate include a process comprising reacting sodium cyanide and acetyl chloride to synthesize acetyl cyanide and hydrolyzing the acetyl cyanide, and a process comprising reacting tartaric acid and potassium hydrogen sulfate. These processes not on…     

Effect of Catalase on Biocatalytic Synthesis of Pyruvate by Enzymes from Pseudomonas sp.

Pyruvate was produced from DL-lactate by a kind of green-chemical biocatalyst --cell-free extract from bacterial strain Pseudomonas sp. SM-6. Catalase in cell-free extract, whichcould stabilize the pyruvate formed by lactate oxidase, played an important role in pyruvatepreparation. The effect of catalase in conversion process was evaluated.     

Asymmetric alkylation catalyzed by chiral alkali metal alkoxides of TADDOL. Synthesis of α-methyl amino acids

It is shown that sodium alkoxides formed from (4R,5R)-2,2-dimethyl-1,3-dioxolane-4,5-bis(diphenylmethanol) ((R,R)-TADDOL) and some of its derivatives can be used as chiral catalysts for enantioselective alkylation of Schiff's bases derived from alanine with reactive alkyl halides. Acid hydrolysis of the reaction products affords (R)-α-methylphenyl-alanine, (R)-α-allylalanine, and (R)-α-methylnaphthylalanine in 61–93% yields and withee 69–94%. When (S,S)-TADDOL is used, the (S)-amino acid is formed. A mechanism explaning the observed features of the reaction is proposed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 926–932, May, 1999.     

Diels-Alder reaction with phosphaalkenes. Synthesis of functionalized λ3 phosphabenzenes.

The reaction of phosphaalkenes (1 and2) with 1,3 dienes such as methyl sorbate and 1-methoxy 3-trimethylsilyloxy-1,3 butadiene leads to functionalized λ³ phosphabenzenes6,9,12,13 and16 after aromatization of the primary adducts. The aromatization may occur either spontaneously or after chemical transformations. The reversible cycloaddition has allowed the synthesis of isomeric phosphabenzenes6 and9. Diels-Alder reaction with phosphaalkenes appears to be a general method for the obtention of functionalized λ³ phosphabenzenes.     

Synthesis of α,β-Unsaturated Nitriles by Reaction of Haloacetonitrile with Carbonyl Compounds Mediated by Tri-n-butylstibine

α,β-Unsaturated nitriles were synthesized by the reaction of haloacetonitriles with carbonyl compounds mediated by tri-n-butylstibine in excellent yields.     

Synthesis of α-methyl ketones by a selective, iridium-catalyzed cyclopropanol ring-opening reaction

A mild method for synthesizing α-methyl ketones from substituted cyclopropanols is reported. This process, catalyzed by [Cp∗IrCl₂]₂, cleaves cyclopropanol rings regioselectively and more efficiently than the other conditions examined. While tertiary cyclopropanols afford α-methyl ketones, secondary cyclopropanols and cyclopropyl silyl ethers are less reactive and yield other isomerization products.     

Synthesis with organoboranes. 21. Synthesis of α- and gd-bamascone

Selective syntheses of α- and gd-damascone, using allylic organoboranes as the key intermediates, are described.     

Synthesis of α-trifluoromethyl-β-keto phosphonates by electrophilic trifluoromethylation with Togni reagent

A new synthetic method of trifluoromethylated phosphonates was developed via electrophilic trifluoromethylation with Togni reagent. A variety of β-keto phosphonates were converted into the corresponding α-trifluoromethyl-β-keto phosphonates in moderate to good yields. This protocol could also be extended to other fluoroalkylation reactions, such as pentafluoroethylation.     

Synthesis ofβ-carboline with the germatrane portion

The 1-oxo-3,3-dimethyl-6-(-trichlorogermyl)ethyl-1,2,3,4-tetrahydroindolo[2,3-c]pyrylium salt, obtained by the acid-catalyzed acylation of 2-(indol-3-yl)dimedone with -trichlorogermylpropionyl chloride and the subsequent reaction with ammonia and triethanolamine, was converted to the corresponding -carboline with the germatrane portion.L. M. Litvinenko Institute of Physicoorganic Chemistry and Carbon Chemistry, Academy of Sciences (NAN) of the Ukraine, Donetsk 340114. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 671–672, May, 1998.     

Synthesis of Betulin-3-yl-β-D-Glucopyranoside

Two concise routes toward betulin-3-yl-β-D-glucopyranoside, being different in the protection of primary alcohol of betulin, were developed. The synthesis adopted a stepwise glycosidation method employing glycosyl trichloroacetimidate as donor.     

Synthesis of conjugates of closo-dodecaborate dianion with cholesterol using a “click” reaction

The nucleophilic ring-opening reaction of tetrahydropyran derivative of the closo-dode-caborate dianion with sodium azide in the presence of tetrabutylammonium bromide led to the novel azido-derivatives of[B₁₂H₁₂]^2?. A Cu-catalyzed 1,3-dipolar [3+2] cycloaddition reaction of the closo-dodecaborate dianion azido-derivatives with alkynyl-cholesterol led to 1,4-disubstituted 1,2,3-triazoles with the closo-dodecaborate fragment at position 1. The resulting conjugates are potentially suitable for the development of liposomal drugs to selectively deliver boron into a tumor cell for boron neutron capture therapy of cancer.

     

Synthesis of Functionalized Δ3 Phosphabenzenes by Means of Diels Alder Reaction with Phosphaalkenes

Abstract

Diels Alder reaction provides an easy and general access to functionalized Δ³ phosphabenzenes after aromatization with the possibilities of introducing the functional group either with the diene or the phosphaalkene.     

Synthesis of novel polyaryl(ether–ketones) with tert-butyl pendent groups

Linear polyaryl(ether ketones) containing tert-butyl pendent groups were prepared from aromatic hydrocarbons and aromatic diacid chlorides, both classes of monomers containing tert-butyl pendent groups. The polymers were prepared in high yield and high molecular weight by low-temperature precipitation polycondensation in 1,2-dichloroethane. The presence of meta-oriented moieties and bulky pendent groups played a beneficial role with regard to solubility, while the thermal transitions and thermal resistance were not greatly impaired relative to conventional all para-oriented polyaryl(ether–ketones). The current polyaryl(ether–ketones) showed glass transition temperatures in the range 170–240°C and decomposition temperatures, as measured by TGA, of about 500°C. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1251–1256, 1998     

Stereoselective construction of an anti-β-alkoxy ether by Ireland-Claisen rearrangement for medium-ring ether synthesis

The asymmetric synthesis of an acyclic anti-β-alkoxy ether was achieved by the Ireland-Claisen rearrangement of Z-3-alkoxy-2-propenyl glycolate ester, prepared from Garner’s aldehyde, a glycolic acid derivative, and ethynyl N,N-diisopropylcarbamate. The resulting acyclic ether was facilely converted to seven- and eight-membered cyclic ethers via processes involving ring-closing olefin metatheses.     

Studies on the reactions of silyl enol ether with perfluoroorganic compounds——Ⅲ.Synthesis of perfluoroalkylated α,β-unsaturated aldehydes and their derivatives

Per-and poly-fluoroalkylated α,β-unsaturated alkenals were synthesized by the reaction of silylenol ether of alkanals with per-and poly-fluoroalkyl iodide initiated by Na_2S_2_O4 conveniently inhigh yield.Their corresponding alkenol and 2,4-dinitrophenylhydrazone were also synthesized.     

Synthesis of Benzoxazolinone by Selenium-Catalyzed Carbonylation with Carbon Monoxide

Ｂｅｎｚｏｘａｚｏｌｉｎｏｎｅｓａｒｅａｋｎｏｗｎｃｌａｓｓｏｆｃｏｍｍｅｒ ｃｉａｌｌｙａｖａｉｌａｂｌｅｃｏｍｐｏｕｎｄｓｔｈａｔａｒｅｗｉｄｅｌｙｕｓｅｄｉｎａ ｇｒｉｃｕｌｔｕｒｅａｎｄｉｎｄｕｓｔｒｙ .Ｔｒａｄｉｔｉｏｎａｌｌｙ ,ｔｈｅｓｅｃｏｍ ｐｏｕｎｄｓａｒｅｍａｄｅｂｙｔｈｅｉｎｔｒａｍｏｌｅｃｕｌａｒｃｙｃｌｉｚａｔｉｏｎｏｆｐｈｅｎｙｌＮ (2 ｈｙｄｒｏｘｙｐｈｅｎｙｌ)ｃａｒｂａｍａｔｅｗｈｉｃｈｉｓｐｒｏｄｕｃｅｄｂｙｔｈｅｒｅａｃｔｉｏｎｏｆｏ ａｍｉｎｏｐｈｅｎｏｌｗｉｔ…     

Water-Insensitive Synthesis of Poly-β-Peptides with Defined Architecture

Biocompatible and proteolysis-resistant poly-β-peptides have broad applications and are dominantly synthesized via the harsh and water-sensitive ring-opening polymerization of β-lactams in a glovebox or using a Schlenk line, catalyzed by the strong base LiN(SiMe₃)₂. We have developed a controllable and water-insensitive ring-opening polymerization of β-amino acid N-thiocarboxyanhydrides (β-NTAs) that can be operated in open vessels to prepare poly-β-peptides in high yields, with diverse functional groups, variable chain length, narrow dispersity and defined architecture. These merits imply wide applications of β-NTA polymerization and resulting poly-β-peptides, which is validated by the finding of a HDP-mimicking poly-β-peptide with potent antimicrobial activities. The living β-NTA polymerization enables the controllable synthesis of random, block copolymers and easy tuning of both terminal groups of polypeptides, which facilitated the unravelling of the antibacterial mechanism using the fluorophore-labelled poly-β-peptide.     

Interaction of aminoquinolines with unsaturated carboxylic acids. 1. Synthesis of N-quinolyl-β-alanines and their biological activity

N-Quinolyl--alanines, and -methyl- and-methyl-N-quinolyl--alanines were prepared by reaction of aminoquinolines and acrylic, methacrylic, and crotonic acids. The corresponding hydrazides and benzylidenehydrazides were obtained. 4-Aminoquinoline with unsaturated acids in water gave betaines. The biological activity of sodium salts of -alanines was investigated.Kaunas University of Technology, Kaunas LT-3028, Lithuania; Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 504–511, April, 2000.