金属锡促进下含氮芳杂环化合物的选择性烯丙基化反应

本文报道了金属锡粉促进下含氮芳杂环的烯丙基化反应。在氯甲酸酯存在下, 利用烯丙基溴和金属锡原位生成的烯丙基锡试剂作为亲核试剂捕捉体系中的N-酰化季铵盐, 合成了一系列烯丙基取代N-酰基杂环衍生物。反应对于咪唑, 噻唑, 吡啶, 嘧啶等含氮含硫的杂环都适用, 并且对于巴豆基溴的反应表现出良好的区域选择性。     

厚朴酚合成方法的改进研究

本实验中,将2,2＇-联苯二酚与1-溴丁烷经Williamson反应后,利用该反应产物溴化钠在酸性条件下与溴酸钠反应生成初生态的溴作为溴源,溴代反应得到5,5＇-二溴-2,2＇-二丁氧基联苯.中间产物5,5＇-二溴-2,2＇-二丁氧基联苯制成Grignard试剂后与烯丙基溴反应生成5,5＇-二烯丙基-2,2＇-二丁氧基...     

锡粉促进下α-酰肼基-γ-戊烯酸乙酯的合成

探索了锡粉促进下,乙醛酸乙酯、酰肼和烯丙基溴的"一锅法"反应.各种酰肼都能参与反应并以高产率生成α-酰肼基-γ-戊烯酸乙酯.当异戊烯基溴和巴豆基溴代替烯丙基溴反应时,得到的都是γ-加成产物.该反应提供了一种合成α-酰肼基-γ-戊烯酸酯化合物的新方法.     

烯丙基溴化钐与α,β-不饱和醛酮反应合成高烯丙基醇

烯丙基溴与金属钐在室温条件下、THF溶剂中反应生成中间体烯丙基溴化钐,烯丙基溴化钐再与α,β-不饱和醛、酮反应生成高烯丙基醇.烯丙基溴化钐与α,β-不饱和醛、酮发生1,2-加成反应,其与α,β-不饱和酮的反应几乎定量进行,表明该反应具有很好的区域选择性.产物的结构通过IR,1H NMR和MS光谱确证.     

水介质中Sm/BiCl~3体系促进下高烯丙基胺的合成

在THF-H~2O(4/1)介质中,Sm/BiCl~3体系促进烯丙基溴与1-(α-胺烷基)-苯并三氮唑反应,生成高烯丙基胺。反应条件中性温和,水介质操作方便,提供了合成高烯丙基胺的一条新的途径。     

水相中铟促进下支链高烯丙基醇的合成

通过铟促进下醛与2-苯基-4-溴-2-丁烯在水相中经烯丙基化反应合成一系列的支链高烯丙基醇, 产率较高, 反应条件温和.     

铟促进的烯丙基硒醚的合成

烯丙基溴和炔丙基溴在铟促进下与二硒化合物反应，生成烯丙基和炔丙基硒醚。反应无需严格的无水无氧条件，烯丙基溴以α-位与二硒化合物反应，产率55%～91%。     

2-甲基-3-芳基烯丙基三苯基溴代鏻的合成

取代苯甲醛经醇醛缩合、硼氢化还原、溴代反应和成盐反应合成了２-甲基-３-间硝基苯基烯丙基三苯基溴化特和２-甲基-３-对硝基苯基烯丙基三苯基溴化鏻两个化合物,收率分别达８６．４％和６９．０％。结构经ＩＲ,1ＨＮＭＰ确证。     

烯丙基卤和锡与醛, 酮反应合成高烯丙基醇

烯丙基溴或烯丙基碘和锡能以较高的产率与含有羟基、酚羟基、硝基、溴等活性基团的羰基化合物作用合成相应的高烯丙基醇, 文中讨论了不同卤素以及溶剂性质、水的含量对反应的影响。     

七-(2,3,6,-O-烯丙基)-β-环糊精的合成与表征

利用氢氧化钠作催化剂使β-环糊精(简称β-CD)被烯丙基修饰合成了七-(2,3,6-O-烯丙基)-β-环糊精[Heptakis-(2,3,6-O-allyl)-β-CD].用正交实验法考察了反应温度、反应时间、催化剂用量和修饰剂--烯丙基溴用量等因素对合成目标化合物的影响,得出合成七-(2,3,6-O-烯丙基)-β-环糊精的最佳实验条件:n(β-环糊精)∶n(烯丙基溴)＝1∶86.92,n(催化剂)∶n(烯丙基溴)＝1∶1.052.产物经元素分析,IR和1H NMR表征和确认.     

Alkylations allyliques catalysees au nickel

Stable enolates such as diethyl malonate enolate can be smoothly substituted by allylic acetates (or sulfones) in the presence of nickel complexes. Sulfinate ions convert allylic acetates into sulfones.     

Direct substitution of primary allylic amines with sulfinate salts

The NH(2) group in primary allylic amines was substituted directly by sulfinate salts with excellent regio- and stereoselectivities. In the presence of 0.1 mol % [Pd(allyl)Cl](2), 0.4 mol % 1,4-bis(diphenylphosphino)butane (dppb), and excess boric acid, a range of α-unbranched primary allylic amines were smoothly substituted with sodium sulfinates in an α-selective fashion to give structurally diverse allylic sulfones in good to excellent yields with exclusive E selectivity. Replacing dppb with 1,1'-bi-2-naphthol (BINOL) allowed unsymmetric α-chiral primary allylic amines to be transformed into the corresponding allylic sulfones in good to excellent yields with excellent retention of ee. Importantly, the reaction complements known asymmetric methods in substrate scope via its unique ability to provide α-chiral allylic sulfones with high optical purity starting from unsymmetric allylic electrophiles.     

Rhodium‐Catalyzed Highly Regio‐ and Enantioselective Hydrogenation of Tetrasubstituted Allenyl Sulfones: An Efficient Access to Chiral Allylic Sulfones

A highly regio‐ and enantioselective hydrogenation of challenging tetrasubstituted allenyl sulfones has been developed, affording chiral allylic sulfones in good yields with excellent regio‐ and enantioselectivities (up to 99 % yield and 99 % ee). This method provides an efficient and concise route to chiral allylic sulfones, thus offering an atom‐economic process with a wide range of potential applications in organic synthesis and medicinal chemistry.     

Carotinoidsynthesen über Sulfone; Synthese von Apocarotinoiden und Torularhodinester

The alkylation of conjugated arylsulfonyl ylids, prepared from the corresponding allylic sulfones (2 or 8), and allylic halides bearing terminal carbonylgroups (3 or 4) leads to polyene sulfones which readily undergo spontaneous elimination of the corresponding aryl sulfinates. By this method two apocarotenoids (5 and 6) and torularhodin ethyl ester (9) have been prepared.     

Synthesis and Reactivity of Allylic and Propargylic Trichloromethanesulfinates

Abstract

The synthesis and rearrangement of the title compounds to sulfones are discussed. A facile isomerization of the allylic trichloromethyl sulfones to the corresponding vinyl sulfones is also described.     

Regio‐ and Enantioselective Preparation of Chiral Allylic Sulfones Featuring Elusive Quaternary Stereocenters

We describe here the first general asymmetric synthesis of sterically encumbered α,α‐disubstituted allylic sulfones via Pd‐catalyzed allylic substitution. The design and application of a new and highly efficient phosphoramidite ligand ( L10 ) proved to be crucial, and a wide variety of challenging allylic sulfones featuring quaternary stereocenters could be obtained in good yields and with good to excellent levels of regio‐ and enantioselectivities under attractive process conditions. The developed methodology employs easily accessible chemical feedstock including racemic allylic precursors and sodium sulfinates. The utility of the method is further demonstrated by the synthesis of the sesquiterpene (?)‐Agelasidine A.     

α-Sulfonyl succinimides: versatile sulfinate donors in Fe-catalyzed, salt-free, neutral allylic substitution

Allyl sulfones are versatile intermediates in organic chemistry. The presence of two distinct functional groups sets the stage for a plethora of subsequent transformations. However, despite these advantages the preparation of regioisomerically enriched sulfones is not easy. The use of sulfinate salts as nucleophiles in substitutions is frequently accompanied by side reactions such as π-bond migration, β-elimination, and so on. Herein we present a preparatively simple way to synthesize a variety of different aryl or alkyl allyl sulfones starting from readily accessible allylic carbonates. By employing aryl or alkyl α-sulfonyl succinimides as sulfinate synthons, mild and regioselective ipso substitution of diverse allylic carbonates was realized.     

Reaction of tri-n-butyltin formate. III. Synthesis of allylic tri-n-butyltin by the reaction of tri-n-butyltin formate with allylic sulfones and sulfides.

Allylic tri-n-butyltins can be prepared easily by the treatment of allylic sulfones or sulfides with tri-n-butyltin formate in refluxing xylene.     

Oxidative dimerization of allylic sulfones with iodine and with ferric chloride

Lithium salts of allylic sulfones are oxidized with ferric chloride-dimethyl-formamide complex mainly to 1,6-disulfones by 3-3′ coupling. Products resulting from coupling of 3,3-disubstituted sulfones undergo Cope rearrangement affording vicinal disulfones with threo-configuration. Coupling with iodine results in mixtures containing mainly vicinal disulfones, again with threo-configuration.     

Highly chemoselective synthesis of aryl allylic sulfoxides through calcium hypobromite oxidation of aryl allylic sulfides

A highly chemoselective oxidation of widely substituted aryl allylic sulfides, prepared by allylation of arylthioethers with KF-Celite, to the corresponding aryl allylic sulfoxide was achieved by employing calcium hypobromite. Neither over-oxidation to sulfones nor halogenation of the aromatic rings was observed. The protocol may be successfully applied for the oxidation of substituted allylic systems (i.e., 2-haloallyl) that per se could interact with the oxidizing agent.