Hosomi sakurai reaction pdf

The hosomi sakurai reaction involves the lewis acidpromoted allylation of various electrophiles with allyltrimethysilane. Highly stereoselective allyl additions are possible. Request pdf sakurai allylation reaction hosomi sakurai reaction lewis acidmediated addition of allylsilanes to carbon nucleophiles. Hosomisakurai reaction of enantioenriched allylsilanes and carbonyls under lewis acidic conditions generally proceeds through a s e mechanism. One of the main characteristics of those reactions is stereospecific chirality transfer from the. Electronic supplementary information catalytic enantioselective hosomisakurai reaction of aketoesters promoted by chiral copperii complexes yutaro niwa, mayu miyake, ichiro hayakawa, akira sakakura graduate school of natural science and technology, okayama university, 311, tsushimanaka, kitaku, okayama, japan table of contents. This reaction was applied to the straightforward enantioselective syntheses of nboc dalloisoleucine 7 and disoleucine 8 from a. Lewis acidpromoted allylation with allyltriorganosilanes, the hosomisakurai reaction, has several advantages over allylations with other allylmetals. Sakurai reaction of allylsilanes containing arabinose.

Bonding, properties and synthetic utility hypervalent silicon. An electrophilic carbon, activated by a lewis acid, is required. A mild and efficient catalytic strecker reaction of nalkoxycarbonylamino sulfones with trimethylsilyl cyanide using indiumiii chloride. Request pdf asymmetric counteraniondirected catalytic hosomisakurai reaction counteranion control enables the enantioselective, organo lewis acid catalyzed hosomisakurai reaction of hetero.

New chiral allylaminosilanes and their use in asymmetric. Several allyltrimethoxysilanes have been synthesized and used for the asymmetric reaction. The key to the success of this system is to turn the usually undesired silylium ion catalysis into the desired catalytic regime and pair the cation with an enantiopure. On the way to an oxidative hosomisakurai reaction full text. Dual activation of both electrophile and nucleophile via a 6membered closed ts in 1987 corriu, hosomi and. The key to the success of this system is to turn the usually undesired silylium ion catalysis into the desired catalytic regime and pair the cation. Counteranion control enables the enantioselective, organo lewis acid catalyzed hosomisakurai reaction of heteroaromatic aldehydes and allylsilanes using an easily handled disulfonimide precatalyst see scheme.

Stereochemical studies of agcatalyzed hosomisakurai. The addition of allylsilanes to carbonyl compounds under lewis acid conditions, first described by sakurai and hosomi,1 has been widely applied to the synthesis of homoallylic alcohols which are important building blocks in organic synthesis, and the possibility of using this reaction for asymmetric synthesis has attracted considerable attention. The catalyst is a chiral complex that contains titanium as a lewis acid. Remarkably, among several possible diastereomers only two are generated with high levels of diastereo. High diastereoselectivity in hosornisakurai reaction on.

An oxidative addition, during which the leaving group. A novel reductive variant of the classical hosomisakurai reaction is reported. All structured data from the file and property namespaces is available under the creative commons cc0 license. In organic chemistry, the keck asymmetric allylation is a chemical reaction that involves the nucleophilic addition of an allyl group to an aldehyde. The hosomisakurai reaction is quite useful for diastereofaceselective allylation of oxocarbenium ions generated from acetals and lactols by treatment with a lewis acid. Total synthesis of dehaloperophoramidine using a highly. The chirality of the catalyst induces a stereoselective addition, so the secondary alcohol of the product has a predictable absolute stereochemistry based on. Total synthesis of dehaloperophoramidine using a highly diastereoselective hosomisakurai reaction ross.

Protonation of that homoallylic ether generates a carbocation which is ideally poised to undergo 1,5hydride transfer, effectively rearranging itself to an oxocarbenium. Files are available under licenses specified on their description page. This operationally simple reaction relies on readily available starting materials and leads to useful products in diastereoselectivities of up to 7. A stereoselective reductive hosomisakurai reaction. Allyl silanes are perhaps the bestknown nucleophiles used hosomisakurai reaction, but boron reagents and others. Asymmetric counteraniondirected catalytic hosomisakurai. Hosomisakurai reactions of silacyclic allyl silanes.

Overall, the trend is consistent with preferential exo grignard or elldo hosomisakurai addition to the sterically less strained anti conformer of the substrate. The tsujitrost reaction is the palladiumcatalyzed allylation of nucleophiles such as active methylenes, enolates, amines and phenols with allylic compounds such as allyl acetates and allyl bromides. Sakurai allylation reaction hosomisakurai reaction. Studies on the reactive species in fluoridemediated. Good generality was demonstrated as both aliphatic and aromatic allylsilanes are effective nucleophiles in additions to the glyoxamide 2. Homoallylic alcohols have long been prepared by the allylation of carbonyls. Only catalytic amounts of lewis acid are needed in some newer protocols. The allylsilane will add to the carbonyl compound directly if the electrophile carbonyl group is not part of an. Lewis acidmediated addition of allylsilanes to carbon nucleophiles. Hosomisakurai reaction an overview sciencedirect topics. The coordination of the pd 0catalyst to the double bond forms an.

We recently reported i an unusual, endoselective, conjugate allylation on 2arylidene1tetralone tricar bonylchromium complex2 by hosomi sakurai reac tion3. Note the use of allylsilyl chlorides instead of allyltrimethylsilane. Asymmetric, antiselective scandiumcatalyzed sakurai. Below is a list of different functional groups that can be used in the hosomi sakurai reaction. A novel reductive variant of the classical hosomi sakurai reaction is reported. This transformation hinges on a redoxneutral, stereoselective internal reduction event under mild conditions. Sakurai reaction of allylsilanes containing arabinosederived alcohols as chiral auxiliaries.