糖基亚苄基NaBH_3 CN-HCl选择性开环过程中乙酰基迁移现象的研究

用NaBH3CN HCl/Et2 O对 3 O 乙酰基 4,6 O 亚苄基 β D 吡喃半乳糖乙硫苷 (2 )进行还原开环 ,发现有乙酰基迁移至 2 位的产物生成 ;进一步的实验表明 ,室温条件下 ,NaBH3CN与 2的作用导致乙酰基的迁移     

狗枣猕猴桃叶化学成分研究(Ⅱ)

从狗枣猕猴桃叶中分离出4个新的黄酮类化合物, 经1D NMR, 2D NMR及ESI-MS等波谱分析鉴定了其结构, 分别是4'-甲氧基-槲皮素-7-O-(4"-O-乙酰基-鼠李糖基)-3-O-β-D-吡喃葡萄糖苷(1), 山柰甲黄素-7-O-(3"-O-乙酰基-鼠李糖基)-3-O-芸香糖苷(2), 山柰酚-7-O-(4"-O-乙酰基-鼠李糖基)-3-O-芸香糖苷(3)和4'-甲氧基-槲皮素-7-O-(4"-O-乙酰基-鼠李糖基)-3-O-芸香糖苷(4).     

保护的几丁寡糖及结构类似物的合成：复杂氨基寡糖合成的通用方法

建立了逐步合成具有重要生物活性的2-脱氧-2-氨基葡萄糖寡糖链的通用方法。采用邻苯二甲酰基保护氨基、硫代苯基为还原末端的离去基团,以氨基葡萄糖为起始原料,几种保护的几丁寡糖及结构类似物被合成：3-O-乙酰基-4,6-O-亚苄基-2-脱氧-2-邻苯二甲酰亚氨基-b-D-吡喃葡萄糖-（1→4）-（3-O-乙酰基-6-O-苄基-2-脱氧-2-邻苯二甲酰亚氨基）-b-D-吡喃葡萄糖甲苷（4）、3-O-乙酰基-4,6-O-亚苄基-2-脱氧-2-邻苯二甲酰亚氨基-b-D-吡喃葡萄糖-（1→4）-（3-O-乙酰基-6-O-苄基-2-脱氧-2-邻苯二甲酰亚氨基-b-D-吡喃葡萄糖）-（1→4）-（3-O-乙酰基-6-O-苄基-2-脱氧-2-邻苯二甲酰亚氨基）-b-D-吡喃葡萄糖甲苷（6）、3-O-乙酰基-4,6-O-亚苄基-2-脱氧-2-邻苯二甲酰亚氨基-b-D-吡喃葡萄糖-（1→3）-（4,6-O-亚苄基-2-脱氧-2-邻苯二甲酰亚氨基）-b-D-吡喃葡萄糖甲苷（8）、3-O-乙酰基-4,6-O-亚苄基-2-脱氧-2-邻苯二甲酰亚氨基-b-D-吡喃葡萄糖-（1→3）-（4,6-O-亚苄基-2-脱氧-2-邻苯二甲酰亚氨基-b-D-吡喃葡萄糖）- （1→3）-（4,6-O-亚苄基-2-脱氧-2-邻苯二甲酰亚氨基）- b-D-吡喃葡萄糖甲苷（10）。所合成化合物通过核磁共振和质谱分析确证了其化学结构。     

2′-O-乙酰基-3-酮基-10,11-脱水-12-O-咪唑酰基-6-O-甲基红霉素的合成

以2′-O-乙酰基-3-羟基-11,12-环碳酸酯-6-O-甲基红霉素为原料,通过DMSO/P2O5氧化其3-羟基;再以六甲基二硅胺基钠为碱,经消除、咪唑酰基化"一锅煮"方法合成了抗生素泰利霉素的关键中间体--2′-O-乙酰基-3-酮基-10,11-脱水-12-O-咪唑酰基-6-O-甲基红霉素,总收率68.3%.     

N6-烷基-2-烷氧基腺苷化合物的合成及抗血小板凝集活性

以鸟瞟呤核苷(1)为原料,经羟基保护得到2’,3’,5’-三-O-乙酰基鸟嘌呤核苷(2),2与三氯氧磷反应得到2-氨基-6-氯-9-(2’,3’,5’-三-O-乙酰基-β-D-呋喃核糖)嘌呤(3),3经重氮化、水解和O-烷基化得到2-烷氧基-6-氯-9-(2’,3’,5’-三-O-乙酰基-β-D-呋喃核糖)嘌呤(4a～...     

1-芳酰基-4-(1＇-N-β-D-吡喃型糖基)氨基硫脲类化合物的合成

通过2,3,4,6-四-O-乙酰基-β-D-吡喃型葡萄糖异硫氰酸酯和2,3,4-三-O-乙酰基-β-D-吡喃型木糖异硫氰酸酯与取代的芳基酰肼的亲核加成反应合成了10个1-芳酰基-4-(1＇-N-2＇,3＇,4＇,6＇-四-O-乙酰基-β-D-吡喃型葡萄糖基)氨基硫脲和7个1-芳酰基-4-(1＇-N-2＇,3＇,4＇-三-O-乙酰基-β-D-吡喃型木糖基)氨基硫脲,所得化合物的结构经元素分析,IR,1H NMR确证.     

D-葡萄糖酸衍生物C5和C6羟基保护基迁移现象研究

2-O-甲基-3,4-O-丙酮叉基-D-葡萄糖酸甲酯(6)的C6羟基用乙酰基保护、C5仲羟基用TBS保护得到化合物8,碳酸钾脱除C6-O-乙酰基时,C5-O-TBS迁移到C6羟基得到了化合物9(74%收率),没有得到目标产物12;将化合物6的C6羟基用TBS保护、C5羟基乙酰基保护的化合物10,四丁基氟化铵脱除C6-O...     

相转移催化法合成1-O-酰基-四-O-乙酰基-β-D-吡喃己糖

以氯化三乙基苄基铵作为相转移催化剂, 用2, 3, 4, 6-四-O-乙酰基-β-D-溴代吡喃葡萄糖和2, 3, 4, 6-四-O-乙酰基-β-D-溴代吡喃半乳糖与羧酸反应, 合成了相应的1-O-酰基-2, 3, 4, 6-四-O-乙酰基-β-D-吡喃葡萄糖和半乳糖。通过解析这些化合物的^1H NMR和红外光谱, 确证其糖甙键构型为β。该相转移催化法具有反应条件温和, 后处理简单和立体选择性强等优点。     

3-烷基/芳基-6-(1'-N-β-D-或-α-L-吡喃型全乙酰化糖基)- 均三唑并[3,4-b]-1,3,4-噻二唑的合成

通过2,3,4,6-四-O-乙酰基-β-D-吡喃型葡萄糖异硫氰酸酯(3)和2,3,4-三-O-乙酰基-α-L-吡喃型鼠李糖异硫氰酸酯(4)与3-烷基/芳基-4-氨基-5-巯基-1,2,4-三唑(5)在乙醇中回流,缩合得到了14个新的3-烷基/芳基-6-(1'-N-2',3',4',6'-四-O-乙酰基-β-D-吡喃型葡萄糖基或2',3',4'-三-O-乙酰基-α-L-吡喃型鼠李糖基)-均三唑并[3,4-b]-1,3,4-噻二唑类化合物(6a-6i,7a-7e),化合物结构经元素分析、IR和1H NMR确证.     

3-O-(β-D-吡喃葡萄糖-1-基)-6-(4-卤代苯基)哒嗪的合成与表征

利用6-(4-卤代苯基)-3(2H)-哒嗪酮的银盐(2)与2,3,4,6-四-O-乙酰基-1-溴-1-脱氧-α-D-吡喃葡萄糖(3)发生Koenigs-knorr反应, 合成了3-O-(2,3,4,6-四-O-乙酰基-β-D-吡喃葡萄糖-1-基)-6-(4-卤代苯基)哒嗪(4),4用干燥的氨气在0℃～-5℃下处理脱乙酰基保护基得相应的3-O-(β-D-吡喃葡萄糖-1-基)-6-(4-卤代苯基)哒嗪(5).其结构经元素分析,IR及1H NMR证实.     

脂族酰基过氧化物分解动力学的分研究 III: 过氧化3,5,5-三甲基己酰在萃中的解动力学和机理

The kinetics of decomposition of 3, 5, 5-trimethylhexanoyl peroxide (1) in benzene has been studied at 30, 40 and 50`C and the cage effect of decomposition has been determined by scavenging method. The relative amounts of the main products of decomposition of 1 at 50`C with change of initial concentration have been determined. The results showed that the decomposition of 1 followed first plus three halves order kinetics as reported for lauroyl peroxide (2), but had a larger cage effect of 0.6. The mechanism of decomposition of 1 is practically the same as what we have proposed for 2. The faster rate and larger cage effect but less induced decomposition of 1 than that of 2 are attributed to the branching of the molecule of 1, especially to the presence of β-methyl group, which causes a larger entropy increase in the transition state.     

Epoxidation and reduction of DHEA, 1,4,6-androstatrien-3-one and 4,6-androstadien-3beta,17beta-diol

Dehydroepiandrosterone (DHEA) reacted with m-chloroperoxybenzoic acid(m-CPBA) to form 3beta-hydroxy-5alpha,6alpha-epoxyandrostan-17-one (1), but it did not react with 30% H2O2. 1,4,6-Androstatrien-3,17-dione (2) was obtained from DHEA and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in dioxane. Compound 2 was reacted with 30%H2O2 and 5% NaOH in methanol to give 1alpha,2alpha-epoxy-4,6-androstadien-3,17-dione (3),which was stereoselectively reduced with NaBH4 to form 1alpha,2alpha-epoxy-4,6-androstadien-3beta,17beta-diol (7) and reacted with Li metal in absolute ethanol-tetrahydrofuran mixture to give 2-ethoxy-1,4,6-androstatrien-3,17-dione (8). Compound 2 was also epoxidized with m-CPBA in dichloromethane to afford 6alpha,7alpha-epoxy-1,4-androstadien-3,17-dione (4),which was reacted with NaBH4 to synthesize 6alpha,7alpha-epoxy-4-androsten-3beta,17beta-diol (9).Compound 4 was reduced with Li metal in absolute ethanol-tetrahydrofuran mixture to form 7beta-ethoxy-6alpha-hydroxy-1,4-androstadien-3,17-dione (10). Compound 2 was reduced with NaBH4 in absolute ethanol to form 4,6-androstadien-3beta,17beta-diol (5), which was reacted with 30% H2O2 to give the original compound, but which reacted with m-CPBAto give 4beta,5beta-epoxy-6-androsten-3beta,17beta-diol (6).     

第五丶六族元素的有机化合物在有机合成中应用的研究 XVIII:氰基亚甲基三苯基胂与酮反应的立体化学以及几种吸电子基团取代的甲基三苯基 砷盐与酮的反应

The stereochemistry of carbonyl olefination reaction of cyanomethylene triphenylarsorane with ketones is reported. The thermodynamically stable E isomer of the products α, β unsaturated nitrile was formed predominantly. Under the experimental conditions we adopted, the reaction conditions had little effect on the E, Z ratio of the reaction products. However, the structure of the substrate showed profound effect. The results shown in Table 1 are similar to that of the reaction of carbomethoxymethylene triphenylarosorane reported in the previous paper. When methyl t-butyl ketone was used as the substrate and the reaction carried out in benzene solution, nearly pure E isomer was obtained. The reaction mechanism was proposed as shown in the previous paper. When Δ4-cholesten-3-one was used as the substrate, change of the solvents showed more prominent effect on the E, Z ratio of the reaction product. This paper also deals with the reaction of three electron-withdrawing group (CN, COOCH3, COCH3) substituted methyltriphenylarsonium salts with ketones in the presence of K2CO3, Na2CO3/benzo-15-crown-5, K2CO3/18-crown-6 or (C2H5)3N in CH3OH solution. The latter three gave satisfactory results (Table 2). The chromotographically pure products could be obtained from the crude products by passing through silica gel column. Its E, Z ratio is nearly the same as that of the crude product. This method seems to be a good one for preparing olefinic compounds in miligram scale.     

无外加催化剂条件下芳香醛与活性亚甲基化合物的缩合反应和迈克尔加成反应

在DMF溶剂中，不外加催化剂使芳香醛(1)与2,2-二甲基-1,3-二氧六环-4,6-二酮(2)发生缩合反应生成2,2-二甲基-5-芳亚甲基-1,3-二氧六环-4,6-二酮(3a～f)。在同样条件下，芳香醛与5,5-二甲基-1,3-环己二酮(4)则发生缩合和迈克尔加成反应生成2,2'-芳亚甲基双(3-羟基5,5-二甲基-2-环己烯-1-酮)(5a～h)。用单晶X-射线分析法确定了产物5b的晶体结构。     

Stereoselective synthesis and crystal structure of 4,6-O- benzylidene-N-octyl-D-allosamine hydrochloride

<正>The building block of N-alkyl derivative of allosamidin(chitinase inhibitor),4,6-O-benzylidene-N-octyl-D-allosamine hydrochloride was stereoselectively synthesized in two steps under mild conditions.Nucleophilic addition of octylamine to 2- oxoglucopyranoside gave a‘carbonyl group transfer' product in 62%yield.Subsequent stereoselective reduction of newly formed C=O with NaBH_4 produced title compound in 75%yield.X-ray diffraction analysis indicates the title compound adopts syn 1,2,3 stereochemistry and chair-chair conformation.The crystal structure is stabilized by hydrogen bonds.     

烷氧基重排反应

本文综述了烷氧基重排反应.根据不同的反应机制,可将烷氧基重排反应分为三类:通过碳正离子重排的烷氧重排反应,分子内烷氧基亲核取代反应和烷氧O-迁移反应.     

无水二氧化镍催化下醋酸烯丙酯与亚膦酸二酯的反应

发现了氯化镍是在双(三甲硅烷基)乙酰胺存在时乙酸烯丙酯与O,O-二烷膦酸酯反应的有用催化剂,反应可在温和条件下以高得率制得烯丙基膦酸酯.     

1.6-缩水-2,4-二-氧-苄基-β-D-吡喃葡萄糖合成、开环及立体选择性成苷反应研究

以较好产率合成了3-位具有不同保护基的1,6-缩水-2,4-二-氧-苄基-β-D-吡喃葡萄糖, 并对其开环反应以及成苷反应的立体选择性进行了研究。     

光学活性3-(1'-羟基乙基)-4- 乙酰氧基-β-内酰胺的立体选择 性合成

(1'R,3R,4R)-N-取代-3-(1'-羟基乙基)-4-乙酰氧基-β-内酰胺(3)是合成青霉烯和碳青霉烯类β-内酰胺抗生素的关键中间体。以廉价的L-抗坏血酸为原料,制得S-缩异丙氧叉甘油醛(5),与胺反应定量转变成相应的手性亚胺(6a～6d),6与双烯酮[2+2]环加成反应,高立体选择性地合成3(S)-乙酰基-β-内酰胺(8a～8d),其非对映体过量由类似反庆的80%提高到接近100%。8a经四步反应得到目标化合物3a。     

NH2(X^2B1)与C2H4反应机理的从头算研究

用从头算MP2方法,在6-311G^**基组下,对NH2X^2B1)与C2H4的加成和氢迁移反应机理进行了研究,优化得到反应的过渡态,并通过振动分析和内禀反应坐标(IRC)加以证实,计算了两个反应的能垒和1500K～2000K温度范围内的速率常数。结果表明：在1500K～2000K温度范围内加成反应是NH2(XX^2B1)与C2H4的反应的主要通道,同时报道了两个反应沿反应路径变化信息。