摘要:
There is provided a method of preparing an epoxide (1a) or (1b) shown below: ##STR1## where R.sup.1, R.sup.2, R.sup.3, and R.sup.4 represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, an alkoxy group, an aryloxy group, an acyl group, an alkyloxycarbonyl group, an aryloxycarbonyl group, allalkyl group, a silyl group, and a silyloxy group; the groups may be bonded with each other to form rings in the case where these groups can be bivalent; these groups may be the same or different, may have substituting groups, or may be branched; and each form (isomer) has a structure in which one side of the plane constituted by double bonds, R.sup.1, R.sup.2, R.sup.3 and R.sup.4, is more seterically hindered in comparison with the other side;characterized in that:an olefin represented by the formula (2) below, is reacted with iodine in the presence of compound generating acyloxy ion, ##STR2## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are the same as defined above; and then the reaction mixture is treated in the presence of a base, thereby forming an oxirane ring stereoselectively on the more sterically hindered side of the olefin.
摘要:
Providing a method of preparing (3R,4R)-3-hydroxy-4-hydroxymethyl-4-butanolide conveniently and selectively from a widely available raw material in a high yield. A carbonyl group of the 2-position of levoglucosenone is reduced to obtain a hydroxyl group of a .beta.-configuration. Then, an iodo-group of an .alpha.-configuration and an acyloxy ion of a .beta.-configuration are introduced regioselectively and stereoselectively to the double bond at the 4-position and the 3-position of the above-mentioned levoglucosenone, respectively, keeping a trans stereochemical relationship. An alkoxide is then formed, by hydrolysis and an oxirane ring of a .beta.-configuration is formed by removing an iodo-group by intramolecular nucleophilic displacement reaction of the alkoxide. After the hydroxyl group of the 2-position is oxidized to convert to a carbonyl group, the oxirane ring is reductively and selectively cleaved, thereby obtaining a chemical compound having no substituent at the 3-position and a hydroxyl group of a .beta.-configuration at the 4-position. Finally a lactone of 5-membered-ring is prepared by subjecting the above-obtained compound to Baeyer-Villigar oxidation.
摘要:
In the method of the present invention for manufacturing 3-DPA-lactone, a protective group is introduced in the first step into the hydroxyl group at 4-position of .gamma.-ribonolactone by an ordinary method. Then, an acid anhydride or an acid chloride is added in the presence of a tertiary amine compound so as to conduct a .beta.-elimination of the hydroxyl group at the 3-position. As a result, a double bond is formed between the 2- and 3-positions and, at the same time, the hydroxyl group at the 2-position is acylated. The double bond between the 2- and 3-positions is reduced in the next step by means of a catalytic hydrogenation. Finally, the protective group of the hydroxyl group is eliminated by an ordinary method. The particular method permits using readily available raw materials, decreasing the number of manufacturing steps, and easily and selectively synthesizing the desired 3-DPA-lactone, which is hardly obtained from nature in a large amount, in high yield, compared with the conventional method.
摘要:
The present invention discloses a method of preparing 3-DPA-lactone, which is difficult to obtain in a large amount from nature. According to the method of the present invention, the target compound can be synthesized at a high yield in fewer steps and more easily than by the conventional synthesizing technique, and selectively from a widely available material. In the method of the present invention, the hydroxyl groups at the 2- and 5 -positions of .gamma.-ribonolactone are protected, and then the hydroxyl group at the 3-position is eliminated so as to form a double bond between the 2- and 3-positions. After that, the protecting groups for the hydroxyl groups are eliminated.
摘要:
After the lactone portion of trans-whiskey lactone is hydrolyzed with potassium hydroxide, this portion is reacted with isopropyl bromide and mixed with an alkyl group, thereby obtaining isopropyl (3S,4S)-4-hydroxy-3-methyloctanoate. Then, the isopropyl (3S,4S)-4-hydroxy-3-methyloctanoate is reacted with diethyl azodicarboxylate in the presence of triphenylphosphine and azodicarboxylate, thereby obtaining isopropyl (3S,4S)-4-(3',5'-dinitrobenzoyloxy)-3-methyloctanoate. The isopropyl (3S,4S)-4-(3',5'-dinitrobenzoyloxy)-3-methyloctanoate is hydrolyzed in 2% potassium hydroxide, and as a result, cis-whiskey lactone (A) represented by the following general formula is obtained. According to this method, cis-whiskey lactone, one of the perfume components of whiskey and wine, can be produced selectively and easily. ##STR1##
摘要:
An acid addition salt of .delta.-aminolevulinic acid is prepared in such a way that tetrahydrofurfurylamine (VI) is reacted with phthalic anhydride under an anhydrous condition to introduce a phthal group which protects amino group of tetrahydrofurfurylamine to give N-tetrahydrofurfuryl phthalimide (III), carbon atoms of the first- and fourth-positions of thus obtained N-tetrahydrofurfurylphthalimide (III) are oxidized at 80.degree. C. using sodium periodate as a oxidizing agent and ruthenium chloride hydrate as a catalyst to yield 5-phthalimidolevulinic acid (II), then the protecting group of 5-phthalimidolevulinic acid (II) is deprotected using an acid to prepare an acid additional salt of .delta.-aminolevulinic acid. The acid additional salt of .delta.-aminolevulinic acid is readily converted by neutralization by an alkali to .delta.-aminolevulinic acid, which is very useful as a precursor of Vitamin B.sub.12, heme and chlorophyll.
摘要:
2,3-Dideoxy-2,2-di(organothio)-B-D-pentofuranosyl-pyrimidines are disclosed as intermediates in the synthesis of 2', 3'-dideoxynucleosides and have the structure shown below. ##STR1## wherein R.sup.4 is a hydroxyl protecting group;X is oxygen or nitrogen, said nitrogen being bonded to a hydrogen atom, an alkyl or acyl group;Y is hydrogen, halogen, alkyl, haloalkyl or haloalkenyl; andR.sup.5 is alkyl, aralkyl, or aryl wherein aralkkyl or aryl is substituted with hydrogen, halogen, nitro or alkoxy.2', 3'-Dideoxynucleosides, products of the above intermediates, are useful as antiviral agents.
摘要:
An alkynyl group having a triple bond at the carbon atom at the 1-position is introduced to a carbon atom at the 1-position of 2,3-O-isopropylidene-D-ribofuranose. The diol part is then cleaved to obtain a lactol compound. This lactol compound is oxidized to obtain a lactone compound. The ketal part of the lactone compound is hydrolyzed and the compound is further subjected to a reduction reaction. The hydroxyl groups at the 2- and 3-positions are then eliminated, and the double bond between the 2- and 3-positions of the resultant compound is reduced to obtain a 4-substituted-.gamma.-lactone.
摘要:
First, levoglucosenone is made to react with methyl lithium in the presence of copper iodide in order to introduce a methyl group into an enone group of levoglucosenone, and to obtain 1,6-anhydro-3,4-dideoxy-4-C-methyl-.beta.-D-erythro-hexopyranose-2-ulose. This methyl compound is oxidized in acetic acid for lactone formation, and (3S,4S)-5-hydroxy-3-methylpentan-4-olide is thus obtained. Further, this lactone is made to react with tosyl chloride in anhydrous pyridine to obtain (3S,4S)-3-methyl-5-tosyloxypentan-4-olide (tosylate). The obtained tosylate is alkylated with n-propyl lithium in the presence of copper iodide to obtain (3S,4R)-3-methyl-4-octanolide. Here, the (3S,4S)-3-methyl-5-tosyloxypentan-4-olide may be treated with potassium carbonate to cleave lactone ring once, thereby obtaining epoxide. After that, the obtained epoxide is alkylated to form lactone ring again to obtain (3S,4R)-3-methyl-4-octanolide.
摘要:
(S)-4-hydroxymethyl-.gamma.-lactone is prepared by oxidizing dihydrolevoglucosenone with a peracid in an organic solvent. (S)-4-hydroxymethyl-.gamma.-lactone is prepared from levoglucosenone. First, levoglucosenone is catalytic hydrogenated, thereby dihydrolevoglucosenone is obtained. Next, dihydrolevoglucosenone thus obtained is oxidized with a peracid in an organic solvent, thereby (S)-4-hydroxymethyl-.gamma.-lactone is obtained. In this manner, (S)-4-hydroxymethyl-.gamma.-lactone can be obtained with high optical purity.