2-甲基-1,8-萘啶衍生物的甲基溴代反应

报道了2-甲基-1,8-萘啶衍生物的甲基溴化反应,以N-溴代琥珀酰亚胺(NBS)为溴化剂、红外光为引发剂,得到单溴代产物2-溴甲基-1,8-萘啶衍生物及其二溴代副产物2-二溴甲基-1,8-萘啶衍生物,对比了两种不同的反应条件,通过对影响甲基溴化产物产率的反应条件进行优化改进,得到单溴代产物的较优合成条件为：NBS的用量为原料的1.2倍,500 W红外灯为光源,反应时间为2 h。 该反应条件下,单溴代产物的产率可达到54.6%。     

3-亚甲基异苯并呋喃-1(3H)-酮的合成

以邻甲基苯甲酸甲酯为原料,经过自由基溴代,Wittig反应,酯水解反应,得到邻乙烯基苯甲酸;随后发生环氧化反应,环合反应得到3-羟甲基异苯并呋喃-1(3H)-酮;再发生亲核取代和消除反应合成了3-亚甲基异苯并呋喃-1(3H)-酮。目标产物在空气中长期放置没有发生二聚。化合物结构用1H NMR、13C NMR和IR表征。     

2-二氟溴甲基-1,3-苯并噻唑的简便合成

本文应用二氟溴乙酸作为二氟溴甲基的合成子,实现了2 巯基芳胺与二氟溴乙酸的缩合反应合成2-二氟溴甲基-1,3-苯并噻唑。该反应以5当量二氟溴乙酸,氯苯为溶剂,于100 ℃下与2-巯基芳胺反应18~40 h,产率高达88%。目标产物通过核磁共振和高分辨质谱表征。该反应条件温和,是对现有合成2-二氟溴甲基-1,3-苯并噻唑的良好补充。     

10-甲基-PGD2的合成子的合成

PGD2的合成子(9)的合成是以2-甲基环戊1,3-二酮(1)为原料, 经烯醇醚化、烯丙基化、酸去保护、羰基的锂铝氢还原、臭氧化、氧化、甲酰化获得.     

乙酰乙酰苯胺类化合物导向的2,2-二溴乙酰苯胺衍生物的合成

以N-溴代丁二酰亚胺(NBS)为溴源,醋酸为催化剂和溶剂,经过活泼亚甲基的两次连续的溴化,羰基的质子化和碳碳键的断裂等过程合成了2,2-二溴乙酰苯胺衍生物.该方法具有操作简便、反应条件温和和高效等特点.所有反应都能以极高的收率得到相应的目标产物.     

2α-甲基-2β-溴甲基青霉烷酸二苯甲酯的合成

以6,6-二氢青霉烷酸二苯甲酯-1-氧化物(Ⅰ)和2-巯基苯并噻唑为原料,通过热裂解开环反应和溴代环合反应,制备得到了β-内酰胺酶抑制剂他唑巴坦关键中间体2α-甲基-2β-溴甲基青霉烷酸二苯甲酯(Ⅲ)。考察了反应温度、反应时间、物料比、催化剂用量对目标产物的影响。结果表明,在n(Ⅱ)∶n(HBr)∶n(Na NO_2)=1∶3∶6,催化剂质量分数为4%,-5℃反应2. 5h的条件下,收率为85. 4%。产物结构经1HNMR、FTIR、MS等技术手段得到验证。     

6-溴(氯)-2-氯甲基-3-喹啉甲酸乙酯的合成方法研究

以邻硝基苯甲醛为起始原料,经还原和氨基保护合成2-乙酰胺基苯甲醛(1)。应用环境友好的聚乙二醇-400为溶剂,以N-卤代丁二酰亚胺为卤代试剂对化合物2-乙酰胺基苯甲醛(1)进行卤代,制备了5-溴(氯)-2-乙酰胺基苯甲醛(2a,2b)。在三甲基氯硅烷(TMSCl)催化作用下,5-溴(氯)-2-乙酰胺基苯甲醛(2a,2b)与4-氯乙酰乙酸乙酯发生Friedlnder缩合反应,合成目标产物6-溴(氯)-2-氯甲基-3-喹啉甲酸乙酯(3a,3b)。其中2a,2b,3a,3b的结构经IR、1H NMR、13C NMR、MS得以确定。     

HBr催化α-溴代甲基酮类化合物的全脱溴反应研究

报道了HBr催化下以水为氢源的α-溴代甲基酮类化合物的脱溴化反应.以α-溴代甲基酮类化合物为原料,四氢呋喃为溶剂,α-溴代甲基酮与质量分数5%的氢溴酸的物质的量比为1.0∶0.2时,在180℃下反应5～14 h,分离产率高达94%[高效液相(HPLC)产率96%]的脱溴产物.该方法无金属催化剂参与,催化剂价格低廉,所有产物均经~1HNMR和~(13)C NMR结构确证.     

2-溴代1,8-萘啶衍生物的合成

以2-羟基-1,8-萘啶衍生物为原料,POBr3为溴化剂,通过简单高效的一步反应合成得到5个2-溴代1,8-萘啶衍生物,分别为2-溴-7-甲基-1,8-萘啶(L1)、2-溴-7-溴甲基-1,8-萘啶(L2)、2-溴-5,7-二甲基-1,8-萘啶(L3)、2-溴-5-甲基-7-溴甲基-1,8-萘啶(L4)和2-溴-5,7-二溴甲基-1,8-萘啶(L5).反应在高温或延长反应时间下易发生自由基取代反应,通过对影响2-溴代1,8-萘啶产物产率的反应条件(反应温度、反应时间、有无自由基猝灭剂)进行优化,得出各2-溴代1,8-萘啶衍生物的最优合成条件.L1和L3的最佳合成条件为60℃反应10min,若高温或延长时间反应,可加入FeCl3或四甲基哌啶氮氧化物(TEMPO)抑制自由基以保证产率;L2的最佳合成条件为80℃反应30min,L4的最佳条件为100℃反应20min,L5的最佳条件为100℃反应30min.优化条件下,各产物产率分别可达62.3%,67.5%,64.2%,56.9%和47.3%.     

2,7-二溴-4-(N,N-二甲基丙烯酰基)芴的合成

以芴为原料,通过溴代、硝化、还原后再与甲基丙烯酰氯反应合成了溴代芴的酰亚胺交联聚合单体——2,7-二溴-4-(N,N-二甲基丙烯酰基)芴,其结构经1H NMR,13C NMR和IR表征。     

Synthesis and some transformations of 2-(2-furyl)naphtho[1,2-<Emphasis Type="Italic">d</Emphasis>]oxazole

By condensation of 1-amino-2-hydroxynaphthalene with furoyl chloride in 1-methyl-2-pyrrolidone 2-(2-furyl)naphtho[1,2-d]oxazole was synthesized and brought into electrophylic substitution reactions: nitration, bromination, sulfonation, formylation, and acylation. The substituent commonly was introduced into the position 5 of the furan ring, but at the nitration and bromination electrophilic attack was directed both at the furan ring and the naphthalene fragment.     

新型5-[10-(9-羧基蒽基)]-间苯二甲酸的合成及荧光性质

以5-氨基-间苯二甲酸二甲酯为原料,经重氮化溴取代、Miyaura硼酸酯化反应生成3,5-二甲氧羰基苯硼酸频哪醇酯(3)。此外,以9-蒽甲酸为原料,经溴化、酯化反应生成10-溴-9-蒽甲酸甲酯(6)。最后以化合物3和6为原料,经Suzuki偶联、水解反应得到目标化合物5-[10-(9-羧基蒽基)]-间苯二甲酸。其结构经1H NMR、13C NMR和高分辨质谱表征。研究结果表明,该化合物钠盐水溶液具有发蓝光的性质,最大发射波长为425nm,同时也有较好的荧光量子效率。     

Synthesis and some transformations of 1-methyl-2-(thiophen-3-yl)-1<Emphasis Type="Italic">H</Emphasis>-benzimidazole

1-Methyl-2-(thiophen-3-yl)-1H-benzimidazole was synthesized by the Weidenhagen reaction, followed by N-methylation. Electrophilic substitution reactions of the title compound, in particular nitration, bromination, sulfonation, formylation, and acylation, were studied. The formylation and acylation in polyphosphoric acid afforded mixtures of 2- and 5-substituted isomers at the thiophene ring. The nitration of 1-methyl-2-(thiophen-3-yl)-1H-benzimidazole involved the thiophene ring or both thiophene and benzene fragments, depending on the conditions. Steric arrangement of the heterocycles in the 1-methyl-2-(thiophen-3-yl)-1H-benzimidazole molecule was analyzed by quantum chemical calculations.     

(±)-19-去甲基-4(18),8,11,13-四烯-松香烷-7-酮的全合成

以间异丙基溴苯1为起始原料,通过进攻环氧乙烷及溴代两步制得溴化物3.溴化物3与Hagemann′s酯发生偶联反应,水解后生成偶联产物5.再以路易斯酸BF3·Et2O催化化合物5进行分子内环化为关键步骤得到反式稠合中间体6,最后通过与三苯基膦碘甲烷季盐发生Wittig反应及氧化,合成了(±)-19-去甲基-4(18),8,11,13-四烯-松香烷-7-酮[19-nor-abieta-4(18),8,11,13-tetraen-7-one](8).     

Synthesis of 2-carbethoxy-3-methyl-4-hydroxybenzofuran derivatives

A number of 2-.carbethoxy-3-methylbenzofuran derivatives were synthesized. A 5,5-gem-dibromo derivative was obtained in the bromination of 2-carbethoxy-3-methyl-4-oxo-4, 5,6,7,tetrahydrobenzofuran. Dehydrobromination of this, dibromo derivative gave 2-carbethoxy-3-methyl-4-hydroxy-5-bromobenzofuran. Depending on the structure of the starting compound and the brominating agent, the bromine in the bromination of 2-carbethoxy-3-methyl-4-hydroxy- and 4-acetoxybenzofurans with bromine and N-bromosuccinimide is incorporated either in the methyl group or in 5 and 7 positions of the benzofuran ring. The nitration of 2-carbethoxy-3-methyl-4-hydroxybenzofuran and its bromo derivative leads to 5-nitro- and 5,7-dinitrobenzofuran derivatives. The structures of the synthesized benzofuran derivatives were established by means of the PMR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 27–29, January, 1980.     

Synthesis of a 4,5-epoxy-2-cyclohexen-1-one derivative via epoxide ring opening, 1,3-carbonyl transposition and epoxide ring regeneration: a synthetic study on a scyphostatin analogue

A 6-alkyl-4,5-epoxy-6-hydroxy-2-cyclohexen-1-one derivative, a model compound for the hydrophilic moiety of scyphostatin, was stereoselectively synthesized from the Diels-Alder adduct. The key steps were the reductive cleavage of the 4,5-epoxide ring of the epoxidated adduct, the 1,3-carbonyl transposition of the 3-carbonyl group to the C1 position by a Wharton reaction and stereoselective bromination to provide a trans bromohydrin derivative, a precursor to the desired compound. Desilylation of the bromohydrin derivative with TBAF directly gave the target compound.     

Regioselective Bromination of a Thymine–Acridine Conjugate by N-Bromosuccinimide

A thymine and acridine conjugate (1), containing a benzylic carbon of thymine and an electron-rich aromatic ring (acridine) within the same molecule, was synthesized. Treatment of 1 with N-bromosuccinimide (NBS) in anhydrous chloroform in the presence of azobisisobutylnitrile produced a dibromo-substituted thymine–acridine conjugate (7) as a major product, in which the bromination was only observed on the acridine ring. Nuclear Overhauser effect (NOE) difference spectroscopy revealed that the actual bromination substitution was on C-2 and C-7 of acridine. Our results suggest that electrophilic aromatic substitution, not the expected benzylic radical reaction, takes place predominantly even when 1 is subjected to the NBS reaction condition, which favors radical processes. In addition, such selectivity is clearly solvent dependent.     

Reaction of 5-(2-furyl)-1-methyl-1<Emphasis Type="Italic">H-</Emphasis> and 1-methyl-5-(2-thienyl)-1<Emphasis Type="Italic">H</Emphasis>-imidazoles with electrophilic reagents

5-(2-Furyl)-1-methyl-1H- and 1-methyl-5-(2-thienyl)-1H-imidazoles were synthesized. The electronwithdrawing effect of the 5- and 2-imidazole substituents on the furan ring was studied by ¹H NMR spectroscopy and quantum-chemical calculations. Some electrophilic substitution reactions were investigated (nitration, bromination, sulfonation, hydroxymethylation, formylation, and acylation). In some cases, depending on the reaction conditions, both the furan and thiophene ring and the imidazole fragment undergo electrophilic attack.     

Synthesis of the fully functionalized ABCDE ring moiety of ciguatoxin

A fully functionalized ABCDE ring moiety of ciguatoxin (CTX), the major causative agent of ciguatera poisoning, was synthesized for the first time. The present strategy involves the efficient installation of the C5-dihydroxybutenyl substituent and construction of the tetrahydrooxepin E ring using a novel alpha-chlorosulfide synthon. [structure: see text]     

Synthesis,Structures, and Near‐IR Absorption of Heterole‐Fused Earring Porphyrins

A reaction sequence of regioselective peripheral bromination, Suzuki–Miyaura coupling with 2‐borylated thiophene or pyrrole, and oxidative ring‐closure with FeCl₃ allowed the synthesis of heterole‐fused earring porphyrins 4Pd and 9Pd from the parent earring porphyrin 1 . Differently pyrrole‐fused porphyrins 5H and 6H and their Pd^II complexes 5Pd and 6Pd were also synthesized. The structures of 4Pd , 5H, 6Pd , and 8Pd have been revealed by X‐ray analysis to be slightly twisted owing to constraints imposed by heterole‐fused structures. 5Pd exhibits an intensified band at 1505 nm, while 4Pd and 9Pd display small but remarkably red‐shifted absorption bands reaching around 2200 nm.