Preparation of amphiphilic polyisobutylenes-b-polyethylenamines by mannich reaction. III. Synthesis of polyisobutylenes-b-polyethylenamines

Copolymers associating α-phenololigoisobutylene and triethylenetetramine blocks in the same chain are prepared by reacting aqueous formaldehyde with α-phenololigoisobutylene and triethylenetetramine. When para-formaldehyde is used instead of monomeric formaldehyde, the reaction does not take place, contrary to what is observed when low molecular weight models are used instead of oligomers. The ability of these copolymers to disperse sludges in motor oil was evaluated by the “spot-test” method. When oil does not contain water, the efficiency of the copolymers is comparable to that of commercial compounds. When oil contains water (1% w) the efficiency of the dispersive agent is drastically reduced. We show that this is due to the presence of phenol group. © 1993 John Wiley & Sons, Inc.     

Preparation of amphiphilic polyisobutylenes-b-polyethylenamines by mannich reaction. I. Synthesis and characterization of α-phenololigoisobutylenes

The cationic polymerization of isobutylene initiated by 4-(2-hydroxy-2-propyl)phenol/BCl₃ system results mainly in α-phenol-ω-chlorooligoisobutylene; however p-(2-chloro-2,4-dimethyl-4-pentyl)phenol is present in all cases. α-Methyl-ω-chlorooligoisobutylene is formed only when the temperature is below?50°C; it results from initiation by the phenol/BCl₃ system. Thermal dehydrochlorination of α-phenol-ω-chlorooligoisobutylene is quantitative and leads to a mixture of isomeric ω-unsaturated oligoisobutylenes. α-Methyl-ω-phenololigoisobutylene is prepared by the Friedel—Crafts reaction between industrial unsaturated oligoisobutylene and phenol in the presence of SnCl₄ at ?30°C; the reaction is quantitative between ?50 and ?30°C degradation takes place. © 1993 John Wiley & Sons, Inc.     

Synthesis of N-propargylanabasine derivatives by the mannich reaction

N-Propargylanabasine derivatives bearing various substituents at the carbon atom of the alkyne fragment were obtained by the reaction of anabasine hydrochloride with terminal alkynes and paraformaldehyde. The reaction proceeded with retention of the C(2) chiral center in anabasine fragment. The by-products of the reaction, including 1,3-diacetylene (the products of dimerization of alkynes) and conjugated vinylacetylenes (the rearrangement products of the Mannich adducts) were isolated and characterized. Dedicated to Academician V. A. Tartakovsky in honor of his 75th anniversary. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1576–1585, August, 2007.     

CeCl_3·7H_2O as an efficient catalyst for one-pot synthesis of β-amino ketones by three-component Mannich reaction

<正>Cerium trichloride heptahydrate(CeCl_3·7H_2O) was found to be an efficient and recyclable catalyst for the three-component direct Mannich reaction of anilines and benzaldehydes with acetophenone.This protocol has advantages of high yield,no environmental pollution,mild condition,and simple work-up procedure.     

Synthetic studies on lycopodine: construction of hexahydrojulolidine core by intramolecular Mannich reaction

The tricyclic core skeleton of lycopodine was constructed by the intramolecular Mannich reaction of a 12-membered cyclic amine. The concise assembly of the macrocyclic intermediate was executed by the sequential inter- and intramolecular N-alkylation of a linear diol using Ns-amide. The fully functionalized diol was prepared via Michael reaction of enone and malonate. The key Mannich reaction proceeded smoothly in the presence of silica gel to provide the tricyclic core skeleton of lycopodine.     

Wittig-Horner反应的动力学研究

Ｗｉｔｔｉｇ Ｈｏｒｎｅｒ反应是Ｗｉｔｔｉｇ反应的一种改进 ,二者可以互相补充 ,但Ｗｉｔｔｉｇ Ｈｏｒｎｅｒ反应还具有某些独特的优点[1] 。Ｗｉｔｔｉｇ Ｈｏｒｎｅｒ反应用于合成的研究有较多的报道 ,但对于该反应的理论研究却不多见[2 ] 。因此 ,我们合成了α 萘甲基磷酸二丁酯 ,并进行了它同一系列取代苯甲醛反应的动力学研究。在磷酸酯及醇钠恒定过量的条件下 ,测定了几种取代苯甲醛反应的假一级速率常数值。但实际上反应属于三级 ,对磷酸酯、乙醇钠和苯甲醛各为一级。因为当改变各反应组份的浓度时 ,速率发生改变。一般Ｗｉｔｔ…     

取代邻苯二酚Mannich反应研究I:

把3-[N,N-双(羧甲基)氨甲基]邻苯二酚和哌啶,吡咯,二乙胺,吗啉和哌嗪在加热可得到相应的5-取位Mannich碱.研究了Mannich反应的机理,理解了这一Mannich反应的定位是由于反应物的分子内氢键.但是在与亚胺基二乙酸反应时或3-吗啉甲基邻苯二酚与吗啉反应,得到正常的6-取代Mannich碱.     

Synthesis of new tridentate chiral aminoalcohols by a multicomponent reaction and their evaluation as ligands for catalytic asymmetric Strecker reaction

A one-step, multicomponent Mannich-type reaction between phenols, paraformaldehyde, and β-aminoalcohols in the presence of LiCl afforded N-2-hydroxybenzyloxazolidines with high ortho-selectivity. Hydrolytic or reductive ring opening of the oxazolidines provided a series of N-salicyl-β-aminoalcohols in 84-92% overall yield. The synthesized compounds were evaluated as ligands for a titanium-catalyzed catalytic asymmetric Strecker reaction. The reaction employing 10 mol % of catalyst provided the Strecker products in excellent yields and up to 98% ee.     

Preparation of amphiphilic graft copolymer with polyisoprene backbone by combination of anionic polymerization and “click” reaction

A novel graft copolymer consisting of polyisoprene backbone and hydrophilic side chain with carbamic acid ester functional group was prepared via thiol-ene"click"reaction and alcohol-isocyanate reactions.Polyisoprene was synthesized by anionic polymerization using n-butyl lithium as initiator,and the pendant hydroxyl groups were introduced by the thiol-ene reaction of mercaptoethanol with the double bond of 1,2-addition units of PI backbone in the presence of radical initiator azobisisobutyronitrile. Isocyanate end group capped poly(ethylene glycol)(mPEG-NCO) was grafted onto the PI backbone through alcoholisocyanate reaction between the pendant hydroxyl groups and isocyanate group of mPEG-NCO.The structure of the graft copolymer were characterized and confirmed by means of size-exclusion chromatography,~1H NMR and FTIR spectroscopy.     

The Meinwald reaction of alkyl propionates. Synthesis of the C1-C9 fragment of aurisides

The C1-C9 northern fragment of aurisides 12a was prepared in eight steps and 41% overall yield starting from Grieco's bicyclic lactone (+)-4. The synthesis features a key stereoselective Meinwald reaction of the lithium enolate of alkyl propionate with the functionalized δ-lactone 3.     

Chain transfer reaction in the polymerization of substituted acetylenes. II. Chain transfer reaction to trimethylvinylsilane in the polymerization of disubstituted acetylenes by MoCl5–n-Bu4Sn

The effect of various olefins as chain transfer agents was studied in the polymerization of 1-chloro-1-octyne, 1-chloro-2-phenylacetylene, 2-octyne, etc., catalyzed by MoCl₅–n-Bu₄Sn (1 : 1). Si-containing olefins, especially trimethylvinylsilane, greatly lowered the polymer molecular weight in the polymerization of the Cl-containing acetylenes, e.g., the M _n of poly(1-chloro-1-octyne) was 4.2 × 10⁵ without an olefin, whereas it decreased to 3.4 × 10⁴, i.e., below 1/10 in the presence of trimethylvinylsilane (1/2 equiv to monomer). In contrast, the molecular weight of poly(2-octyne) did not decrease that much, even with trimethylvinylsilane. The Cl-containing polyacetylenes obtained in the presence of trimethylvinylsilane as chain transfer agent possessed the trimethylsilyl group. Thus, the present study enables control of the molecular weight of substituted polyacetylenes by chain transfer, and further verifies the metal carbene mechanism for the polymerization of substituted acetylenes. © 1993 John Wiley & Sons, Inc.     

Facile synthesis of aminonaphthoquinone Mannich bases by noncatalytic multicomponent reaction

Mannich bases are formed in a noncatalytic multicomponent reaction, which is promoted by ultrasound irradiation. The procedure avoids the use of toxic solvents, catalyst, and purification, generating the desired compounds in excellent yields and short reaction times.     

Factors affecting the efficiency and stereoselectivity of α-amino acid synthesis by the Petasis reaction

The use of chiral secondary amines containing only one branched substituent has been shown to give optimal yields and stereoselectivities in the preparation of α-amino acids using the Petasis reaction. While the use of chiral primary amines generally gives products in low to moderate diastereoselectivity, chiral secondary amines generally give products in >95:5 diastereoselectivity. Additionally, the use of amines with two chiral (and by definition, branched) N-alkyl substituents results in significantly reduced yields with respect to to secondary amines with one or no branched N-alkyl substituents.     

取代苯酚的定量结构－活性／性质相关性研究

在分子拓扑理论基础上,提出了一个新的价连接性指数~nG=∑(E_i·E_j· E_k...),其中~0G=∑(E_i),~1G=∑(E_i·E_j),并用~0G,~1G研究了取代苯酚（ 含Cl,Br,INH_2,NO_2,COOH,烷基、环烷基、苯基等）的溶解度,辛醇／水分 配系数及对黑曲霉、浮萍、细胞色素P－450、酵母菌等的生物活性,给出了相关方 程。结果表明,新方法计算简单,使用方便,预测值与相应的实验值较好吻合。     

铜胺络合物作用下取代2-萘酚的交叉偶合反应

在铜(II)-胺络合物作用下, 取代2-萘酚化合物进行交叉偶合反应, 得到几种结构新颖的取代1,1'-联-2-萘酚化合物, 产率44%～90%. 化合物的结构经过核磁、红外光谱及质谱进行确证.     

Catalytic asymmetric synthesis of spirooxindoles by a mannich-type reaction of isothiocyanato oxindoles

Easy access: a strontium/Schiff base complex as catalyst for the title reaction provided straightforward access to enantiomerically enriched spiro[imidazolidine-4,3'-oxindole] compounds, as well as a spiro[imidazoline-4,3'-oxindole] through a two-step conversion from the Mannich adduct.     

Enantioselective direct Mannich reaction of functionalized acetonitrile to N-Boc imines catalyzed by quaternary phosphonium catalysis

Quaternary phosphonium ion-pair or a salt derived from amino acid has been developed to catalyze the Mannich-type reaction of α-substituted ethyl cyanoacetates and 2-(2-nitrophenyl) acetonitrile to N-Boc imines. Experiments shown that more active cyanoacetates could be catalyzed by the gentle phosphonium ion-pair catalysis, while 2-(2-nitrophenyl) acetonitrile as the substrate has to be activated by quaternary phosphonium salts and strong base. All the reactions gave the corresponding highly functionalized chiral β-amino nitriles products with good yields, high diastereo- and enantioselectivities in mild conditions.