一种新的聚合物固载的1,3-二醇的合成及其对二醛的单保护性能

聚合物固载的1,2-二醇(1—3)和1,3-二醇(4,5)作为醛或酮的保护基团已有广泛的研究。聚合物固载的保护试剂的重要特性是能够对双功能基化合物进行单保护。上述二醇树脂用于对苯二甲醛单保护中只有在很低的醛固载量(0.2—0.38mmol/g)时才是成功的。其单保护率可达95％以上。一旦固载的醛量增加,其单保护率迅速降低。而且这些二醇树脂多数不能再生重复使用。从这些二醇聚合物的结构分析可以看出,它们对二醛单保护率低的原因很可能是功能基通过醚键或酯键同聚合物相连,其柔性增加了二醛双结合的可能性。为了克服这些树脂的缺点,我们设计合成了二醇功能基直接与聚苯乙烯链的苯环相接的1,3-二醇树脂——1-聚苯乙烯基-2,2-二甲基-1,3-丙二醇(6)。二醇功能基2位上的两个氢原子均被甲基所取代,减少了在被保护的醛解脱过程中二醇功能基脱水失活的可能性,以增加功能基的可再生性。     

2-十六烷氧基-5-羟甲基-1,3-苯二甲醛的合成

以对羟基苯甲醛为原料,经酚的二溴代、酚羟基的烷基化、醛的还原、醇羟基的保护、二甲酰化、去保护六步反应合成了2-十六烷氧基-5-羟甲基-1,3-苯二甲醛,其结构经1H NMR,IR和HR-MS确证。     

BAL-树脂的合成及其在对称二醛单功能基Wittig反应上的应用

<正> 近年来,有机化学家应用不溶性聚合物试剂α-二醇、β-二醇树脂对二元醛酮单功能化反应做了大量的工作。笔者在相转移催化下,用交联的氯甲基化聚苯乙烯与2,3-二巯基丙醇(BAL)进行Williamson反应,合成了一个新的不溶性聚合物醛酮保护试剂——BAL-树酯Ⅲ(巯基容量=2.5m mol/g)。并利用鱼钓原理以Ⅲ与对称二醛(对苯二甲     

藏红花酸二醛的合成研究（英文）

本文提供了一种简单方便的合成2,6,11,15-四甲基-2,4,6,8,10,12,14-十六碳七烯二醛(藏红花酸二醛)的方法,即通过2,7-二甲基-2,4,6-辛三烯二醛与3-(5,5-二甲基-1,3-二恶烷-2-基)丁-2-烯基膦酸二乙酯或(3-甲基-4-氧代-2-丁烯-1-基)膦酸二乙酯进行霍纳尔-沃兹沃思-埃蒙斯(HWE)反应,以四氢呋喃为溶剂,氢化钠或叔丁醇钾为碱来合成藏红花酸二醛。所得到的化合物经过红外,核磁共振氢谱,碳谱以及质谱确认。     

手性双氨基醇-Et2Zn催化的不对称直接羟醛缩合反应

以1,3-二溴丙酮和(2'S)-(二苯基羟甲基)-四氢吡咯为原料,合成了两种新型手性氨基醇1,3-双[(2'S)-(二苯基羟甲基)-1-四氢吡咯基]丙酮(3)和1,3-双[(2'S)-(二苯基羟甲基)-1-四氢吡咯基]-2-丙醇(4),总产率分别为39%和35%.手性双氨基醇3-/4-Et2Zn可催化未修饰醛、酮的不对称直接羟醛缩合反应,对映体过量最高9%.     

5-[(3-吲哚基)-甲基]-2,2-二甲基-1,3-二噁烷-4,6-二酮衍生物的高效合成

在分子碘作用下,以吲哚、醛和2,2-二甲基-1,3-二噁烷-4,6-二酮为原料,通过三组分缩合反应合成了10种5-[(3-吲哚基)-甲基]-2,2-二甲基-1,3-二噁烷-4,6-二酮衍生物。 当催化剂的用量为5%(摩尔分数)时,30 ℃反应60~90 min,收率为71.4%~97.3%。 此外,还探讨了分子碘的催化机理。     

1,3-二烷氧基-乙酰丙酮和-丙酮的[1,3] 键迁移重排

1,3-二甲氧基-2-吗啉-N-基戊1-烯-4-酮(11a)的酸水解经证实发生部分重排, 生成1,3-(1a)和1,5-二甲氧基乙酰丙酮(2a)的混合物, 并通过与氰基乙酰胺缩合, 分别形成3-氰基-4-甲氧甲基-5-甲氧基-6-甲基吡啶-2-醇(3a)和3-氰基-4,6-双(甲氧甲基)吡啶-2-醇(4a)加以证实, 前者还转化为维生素B6. 在相应的乙氧基序列中, 除得到1b丶2b丶3b和4b外, 还分离了反向缩合产物3-氰基-4-甲基-5-乙氧基-6-乙氧甲基吡啶-2-醇(5b) . 对Fedoronko 等为1,3-二甲氧基丙酮的重排-水解为丙酮醛提出的烯丙型重排机制提出了质疑. 事实上, 这一重排更可能是一利热过程的[1.3]单键迁移过程和提供了支持的事例.     

1,3-二烷氧基-乙酰丙酮和-丙酮的[1.3]σ键迁移重排

1,3-二甲氧基-2-吗啉-N-基戊-1-烯-4-酮(11a)的酸水解经证实发生部分重排,生成1,3-(1a)和1,5-二甲氧基乙酰丙酮(2a)的混合物,并通过与氰基乙酰胺缩合,分别形成3-氰基-4-甲氧甲基-5-甲氧基-6-甲基吡啶-2-醇(3a)和3-氰基-4,6-双(甲氧甲基)吡啶-2-醇(4a)加以证实,前者还转化为维生素 B_6.在相应的乙氧基序列中,除得到1b、2b、3b 和4b 外,还分离了反向缩合产物3-氰基-4-甲基-5-乙氧基-6-乙氧甲基吡啶-2-醇(5b).对 Fedoronko 等为1,3-二甲氧基丙酮的重排-水解为丙酮醛提出的烯丙型重排机制提出了质疑.事实上,这一重排更可能是一种热过程的[1.3]单键迁移过程和提供了支持的事例.     

ATRP法合成结构对称的双羧基聚苯乙烯及其超分子的形成

从二甲苯出发,经过溴甲基化反应、氧化反应、酯化反应和溴代反应,合成了一种四官能团的引发剂,4,6-二(溴甲基)-1,3-苯二甲酸二甲酯.用该引发剂引发苯乙烯进行原子转移自由基聚合,实验结果表明聚合反应具有活性自由基聚合的特征.通过苯乙烯的本体聚合反应获得了分子量可控、双酯基位于聚合物链中间的聚苯乙烯.经过水解反应,使聚合物中的双酯基被水解成双羧基,从而得到了结构对称的两亲性聚合物,双羧基聚苯乙烯.利用该聚合物具有分子识别的特性,与十二烷胺形成了离子键超分子化合物.此工作为超分子星形聚合物的设计合成提供了简便快捷的方法.     

醋酸铜催化“一锅法”合成5-(1-苯基-3-苯基丙基-2-炔基)-2,2-二甲基-1,3-二噁烷-4,6-二酮衍生物

在醋酸铜催化作用下,以抗坏血酸钠为还原剂,以醛、2,2-二甲基-1,3-二噁烷-4,6-二酮和苯乙炔为原料,通过包含Knoevenagel缩合与Conjugate加成反应的多组分反应,有效地合成了10种5-(1-苯基-3-苯基丙基-2-炔基)-2,2-二甲基-1,3-二噁烷-4,6-二酮衍生物.该工艺具有收率高(63%～86%)、反应温和、操作简单及环境友好等优点,为合成5-(3-苯基-1-苯基丙基-2-炔基)-2,2-二甲基-1,3-二噁烷-4,6-二酮衍生物提供了一种有效的方法.     

Solid-phase synthesis of 1,2,3-triazoles via 1,3-dipolar cycloaddition

The solid-phase synthesis of 1,2,3-triazoles via 1,3-dipolar cycloaddition of polymer-bound azides to various alkynes is reported. Polymer-bound azides were synthesized from polymer-bound halides and sodium azide and reacted with alkynes to produce polymer-bound 1,2,3-triazoles. Cleavage of the triazoles was performed with trifluoroacetic acid. A traceless synthesis of 1,2,3-triazoles was developed using 2-methoxy-substituted resin (polymer-bound 4-hydroxy-2-methoxybenzyl alcohol). In addition, a synthesis of 4-hydroxybenzyl-substituted 1,2,3-triazoles from the bromo-Wang resin (4-(bromomethyl)phenoxymethyl polystyrene) was achieved.     

Synthesis of a Polymer-bound Sensitizer and its Application in the Photoisomerization of trans-Vitamin D_3 to cis-Vitamin D_3

The photochemistry of the vitamin D family and their precursors has been the subject of extensive studies for many years1-4. Most of the studies focus on the photoisomer- ization of 7-dehydrocholesterol and that of tachysterol to previtamin D3, which is of commercial importance in the synthesis of vitamin D34, 5. Recently the cis/trans isomerization of vitamin D analogs (Scheme 1) draws attention because of its importance in the synthesis of hydroxylated vitamin D metabolites6. However, o…     

Efficient solid-phase synthesis of a library of imidazo[1,2-a]pyridine-8-carboxamides

A versatile method for the solid-phase synthesis of imidazo[1,2-a]pyridine-based derivatives, imidazo[1,2-a]pyridine-8-carboxamides, has been developed. They were obtained by treatment of the amino group of the polymer-bound 2-aminonicotinate with different alpha-haloketones, followed by halogenation at the 3-position of the polymer-bound imidazo[1,2-a]pyridine. The derived polymer-bound imidazo[1,2-a]pyridines 5, 6, and 7 were finally cleaved from the solid-support with an excess of primary or secondary amines. The final crude products were purified from excess amines by solid-supported liquid-liquid extraction (SLE).     

Synthesis of polymer-bound 4-acetoxy-3-phenylbenzaldehyde derivatives: applications in solid-phase organic synthesis

Aminomethyl polystyrene resin was reacted with 4-(5'-formyl-2'-hydroxyphenyl)benzoic acid and 4-(5'-formyl-2'-hydroxyphenyl)phenyl propionic acid, respectively, in the presence of 1-hydroxybenzotriazole and 1,3-diisopropylcarbodiimide to yield polymer-bound benzaldehydes. The phenolic group in resins was acetylated with acetic anhydride to afford two polymer-bound 4-acetoxybenzaldehydes. The reductive amination of polymer-bound linkers by amines and sodium triacetoxyborohydride, followed by sulfonylation with arylsulfonyl chloride derivatives in the presence of pyridine and the cleavage with TFA/DCM/H2O, produced pure sulfonamides.     

Solid-phase synthesis of pyrazolopyridines from polymer-bound alkyne and azomethine imines

Study was made of the 1,3-dipolar cycloaddition of polymer-bound alkynes to azomethine imines generated in situ from N-aminopyridine iodides. Aromatization of the cycloadducts gives polymer-bound pyrazolopyridines that can be released from the resin as carboxylic acids with trifluoroacetic acid or as methyl esters with sodium methoxide.     

Photophysical Behavior of Zinc(II) Tetraphenylporphyrin Covalently Incorporated in a Cholesterol-Bearing Polymethacrylate

Photophysical behavior of a zinc(II) tetraphenylporphyrin (ZnTPP) moiety in a copolymer of 0.1 mol % zinc(II) 5-[4-(6-methacryloyloxyhexanoyloxy)phenyl]-10,15,20-triphenylporphynate (ZnTPP-C₅-MA) and 99.9 mol % cholesteryl 6-methacryloyloxyhexanate (Chol-C₅-MA) was investigated in comparison with that of monomeric ZnTPP-C₅-MA. Pendant cholesterol (Chol) groups in the copolymer form stacks in n -hexane (a poor solvent for the copolymer), while no Chol stacks are formed in benzene (a good solvent). The absorption maxima of the Soret and Q bands of monomeric ZnTPP-C₅-MA were solvent dependent, i.e. the maxima in n -hexane were 7.6 nm shorter than those in benzene. In contrast, no such solvent dependence was observed for the polymer-bound ZnTPP moiety. Spectral profiles for the fluorescence bands for the polymer-bound ZnTPP moiety and monomeric ZnTPP-C₅-MA were very different in n -hexane, i.e. the relative intensity of the 0–0 to 0–1 fluorescence bands for the former was 0.52 while that for the latter was 1.10. The triplet excited lifetime for the polymer-bound Zn-TPP moiety at room temperature was much longer in n -hexane (22 ms) than in benzene (3.7 ms), while the fluorescence lifetime at room temperature was slightly longer in n -hexane (2.52 ns) than in benzene (2.09 ns). The polymer-bound ZnTPP moiety emitted phosphorescence and E-type delayed fluorescence in n-hexane at room temperature, arising from the long triplet lifetime. Fluorescence quenching for the polymer-bound ZnTPP moiety by vitamin-K₃ was suppressed in n -hexane, as compared to the quenching of the monomer. All these observations indicate that the ZnTPP chromophores in the copolymer are "protected" in the Chol stacks in n-hexane, leading to an isolation of ZnTPP from the bulk solution phase.     

聚苯乙烯苄基(8-氨基喹啉)负载鈀催化剂的催化加氢性能

本文在带有8-氨基喹啉螯合基团的树脂上负载了二氯化钯,再经甲醇-水还原合成混合价态钯催化剂。考察并比较了两类催化剂的加氢活性及选择性,发现混合价态钯催化剂具有活性高、选择性强、金属不易流失的特点。     

Solid-phase rhodium carbenoid N-H insertion reactions: the synthesis of a diverse array of indoles

A solid-phase synthesis of an array of indoles is reported. The key step in our approach involves a N-H insertion reaction of N-alkylanilines into a highly reactive polymer-bound rhodium carbenoid intermediate to yield the corresponding alpha-arylamino-beta-ketoester. These insertion products were then treated under acid-catalyzed cyclodehydration conditions to yield a series of polymer-bound indole esters, which were subsequently cleaved from the resin under Lewis acid-promoted amidation conditions to yield the desired indoles in good yields and with excellent purities.     

Crossed aldol reaction using cross-linked polymer-bound lithium dialkylamide

Cross-linked polymer-bound lithium dialkylamides were employed in crossed aldol reaction of various carbonyl compounds with aldehydes to afford the corresponding β-hydroxycarbonyl compounds. The introduction of spacer chains to the polymer-bound lithium dialkylamide between the base moiety and the polystyrene backbone effectively enhanced yields of the desired aldol adducts. Sometimes better yields were obtained by using the polymer-bound reagent having an appropriate spacer-chain with those obtained using lithium diisopropylamide under homogeneous conditions. Repeated use of these polymeric reagents was demonstrated with no loss of efficiency.     

One-pot solid phase synthesis of (E)-nitroalkenes

An efficient one-pot protocol for the synthesis of (E)-nitroalkenes by reaction of aldehydes and nitroalkanes in the presence of polymer-bound triphenylphosphine, iodine and imidazole is described. Although the reaction works with similar efficiency with triphenylphosphine and its polymer-bound version, easy removal of the unwanted polymer-bound triphenylphosphine oxide and its recovery as triphenylphosphine provide the edge for practical application of the method.