Synthesis of β-fluoro-β-proline

A synthetic strategy towards the novel amino acid β-fluoro-β-proline, a fluorinated analogue of β-proline, is elaborated. The synthesis commences from commercially available methyl 2-fluoroacrylate and involves three steps. The overall yield of β-fluoro-β-proline is 57%.     

First Total Synthesis of 4,5-Secoeudesmane-type and Iphionane-type Compounds——Synthesis of 4,5-Dioxo-seco-γ-eudesmol and 5β,11-Dihydroxyiphionan-4-one

4,5-Secoeudesmane-type and iphionane-type compounds are sesquiterpenes with new carbon skeletons found in natrual sources in recent years.^1-6 The Co-occurence of 4,5-secoeudesmanes, iphionanes and eudesmanes as natrual products suggests that 4,5-secoeudesmanes, iphionanes most likely are generated biogenetically from eudesmanes, and iphionanes are formed biogenetically by aldol reaction of 4,5-dioxosecoeudesmanes.^1,4,6,7 The study on the synthesis of this two kind of new sesquiterpenes has not been reported in the literature.     

First Total Synthesis of 4,5-Sccoeudesmane-type and Iphionane-type Compounds-Synthesis of 4,5-Dioxo-seco-γ-eudesmol and 5β,11-Dihydroxyiphionan-4-one

4, 5-Secoeudesmane-type and iphionane-type compounds are sesquiterpenes with newcarbon skeletons found in natrual sources in recent years.1-6 The co-occurence of 4, 5secoeudesmanes, iphionanes and eudesmanes as natrual products suggests that 4, 5secoeudesmanes, iphionanes most likely are generated biogenetically tyom eudesmanes,and iphionanes are formed biogenetically by aldol reaction of 4, 5dioxosecoeudesmanes1,4,6,7 The study on the synthesis of this two kind of newsesquiterpenes has not be…     

Synthesis of Deoxytabtoxinine-β-Lactam

Deoxytabtoxinine-β-lactam (12) was synthesized in 6 steps from 3. β-Lactam 12 does not inhibit glutamine synthetase indicating that the hydroxyl group of tabtoxinine-β-lactam (2) is necessary for inhibition of glutamine synthetase.     

Synthesis of 15β, 16β-methyleneprogesterone

15,16-Methyleneprogesterone was produced from 15,16-methylene-3-hydroxyandrost-5-en-17-one with Wittig olefination of 17-ketone by methoxymethylenetriphenylphosphorane as the key stage.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 203–207, January, 1993.     

Synthesis of 5-O-β-Iodoethyl-D-Glucofuranose

ABSTRACT

The preparation of an iodinated derivative of D-glucose where a β-iodoethyl moiety has been introduced at O-5 is presented. In such an analogue the existence of pyranose forms is precluded and the iodinated tag lies in a region of the carbohydrate not judged essential for recognition by the glucose transport protein; also noteworthy in such a compound is the stability of the carbon-iodine bond, a prerequisite for its potential use in SPECT medical imaging.     

Synthesis of aryl-β-chlorovinyl ketones

Summary A method was developed for the synthesis of aryl--chloxovinyl ketone by condensation of substituted acetophenones with ethyl formale followed by treatment of the resultant hydroxymethylene ketone with thionyl chloride.     

Synthesis of (+)-β-Bisabolene

β-Bisabolene (1) is one of the simplest monocyclic sesqui-terpenes found in nature.¹ Many syntheses² involving chain extension on cyclohexenyl derivatives have been published. We now wish to describe a new route which features a Diels-Alder reaction to assemble all but one carbon atom of the sesquiterpene.     

Synthesis of 1,2:4,5-di-O-Isopropylidene-3-C-Cyano-β-D-ribo-hex-2-ulo Pyranose by Phase Transition Catalysis

Introduction The cyano branched carbohydrates are useful, versatil intermediaries for the synthesis of branched sugars having biological activity in nature. Owing to the good yield, mild reaction conditions and high stereospecificity, the phase transition catalysis(PTC)method has been widely used to the syntheses of C-     

Synthesis and transformations of 2β,3β-diacetoxy-20-(4,5-dihydroisoxazol-5-yl)-6-oxo steroids

20-Hydroxy-20-(4,5-dihydroisoxazol-5-yl) steroid was brought into reactions typical of functionalization of rings A and B in ecdysteroids. The dihydroisoxazole ring remained unchanged in reactions leading to formation of the 2,3-dihydroxy-6-oxo moiety. The isomerization of 5-bromo derivative in acetic acid in the presence of a catalytic amount of hydrobromic acid and Lewis acids is accompanied by elimination of the hydroxy group from C²⁰ and subsequent migration of the double bond to the heteroring to afford the corresponding isoxazole derivative.Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 10, 2004, pp. 1500–1505.Original Russian Text Copyright © 2004 by Litvinovskaya, Drach, Khripach.     

Synthesis of esters of α-chloroacetoxy-β,β,β,-trichloroethylphosphonic acids

Summary The synthesis of 11 previously unreported dialkyl esters of -mono-, -di-, and -trichloroacetoxy-,,-trichloroethylphosphonic acids has been effected.     

β-Cyclodextrin Mediated Synthesis of Syndiotactic-rich Polystyrene

Stereoregular polystyrene (PS) was prepared using various molarequivalents of -cyclodextrin (-CD) by polymerisingstyrene in the presence of -CD. Stereoregular (isotactic,atactic and syndiotactic) distributions of the preparedpolystyrene polymers were determined from terminal modelBernoullian statistics using ¹³C NMR data. Inclusioncomplexation of styrene by -cyclodextrin was detected byUV-Visible spectroscopy, which gave a binding constant value of31606 ± 3350 M^-1 for the 1 : 1 complex. With anincrease in the styrene : -CD ratios, the proportionof syndiotactic polymers increased. The glass transitiontemperature (T_g) of the polymer also increased along withmelting temperature (T_m) at higher styrene : -CDratios. In addition, the molecular weight of the polymers prepareddecreased with increase in the -CD concentration.     

Synthesis of Spiro-β-Methylene-γ-Butyrolactones

The Bakkenolide group 1 ³ of sesquiterpenes present two interesting synthetic problems. The cisdimethyl cis-hydrindane portion 2, because of its structural and stereochemical relationship with the eremophilane sesqui terpenes,⁴ has synthetic solutions available.⁵ The spiro-β-methylene-γ-butyrolactone unit 3,⁶ which is presently unique to this class of natural products, has been synthesised by four different routes.^7–10     

Synthesis of 6β-Halogenodeoxyneopine from Neopine

(-)-Neopine (1), the Δ^8,14 isomer of codeine, occurs as one of the minor constituents in opium from Papaver somniferum L¹. In opium alkaloids of the morphine group the hydroxyl group in position 6 is readily converted with p-toluenesulfonyl chloride or methanesulfonyl chloride into the respective 6α-O-sulfonyl derivatives². The latter in turn form starting materials for the preparation of other derivatives. Thus, with lithium halides, via a S_N2 mechanism³ the 6β-halogen compounds are formed. It is found that, as a result of the allylic system, under slightly changed reaction conditions codeine itself can also yield the 8β-chloro derivative⁴.     

Synthesis of Trideuteriomethyl 5-Deuterium-β-D-Mannopyranoside

Abstract

The title compound was prepared by first converting trideuteriomethyl 2,3,4-tri-O-benzyl-β-D-mannopyranoside to a 6-bromo-6-deoxy derivative which on elimination by using DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) or DBN (1,5-diazabi-cyclo[4.3.0]non-5-ene) gave a hex-5-enopyranoside derivative. The deuteroboration of the hex-5-enopyranoside followed by oxidation and subsequent deblocking produced trideuteriomethyl 5-deuterium-β-D-mannopyranoside.     

Synthesis of 3,6-di-O-methyl-β-d-glucopyranose conjugates

3,6-Di-O-methyl-β-d-glucopyranose neoglycoconjugates with bovine serum albumine and poly(acrylamide) carrier were obtained, which differ in the aglycon nature, linking pattern, and substitution degree.     

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 α-amino-β-keto-esters (β-oxodipeptides)

The synthesis of α-amino-β-keto-esters (β-oxo dipeptides) was studied. Corresponding α-amino-β-ketoesters were prepared from BOC-(L)-Valine and BOC-(L)-isoleucine by coupling with (D,L)-threonine hydrochloride and oxidation with Dess-Martin periodinane (DMP) with a total yield of 48% and 38%, respectively. __________ Translated from Chemistry Online, 2007, 70(10): 793–796 [译自: 化学通报]     

Synthesis and Crystal Structure of 4,5-Diazafluorene-9-one Azine Hydrochloride Hydrate

1 INTRODUCTION During the study of polynuclear complexes with the aim to investigate the magnetic super-exchange interaction between the adjacent metal ions bridged by a conjugation molecule[1], we have made efforts to prepare complexes bridged by 4, 5-diazafluorene-9-one azine (DAA) and found that the coordination ability of DAA is poor in the acidic solution. In order to probe the reason, DAA has been crystallized from the hydrochloric acid solution and its crystal structure has b…