Stille cross coupling Scope

Carreira and co-workers have also extended the scope of aldehydes that may be utilized in catalytic addition reactions to include stannylpropenal 108 as a substrate (Table 8B2.12, Entry 7). The adduct produced from the aldol addition of 105 is isolated with 92% ee and serves as a useful building block, as it is amenable for further synthetic elaboration (Scheme 8B2.9). Thus, vinylstannane 109 is a substrate for Stille cross-coupling reactions to give a diverse family of protected acetoacetate adducts 110. Following deprotection of the masked keto ester, the corresponding hydroxy keto ester 111 may be converted to either the syn or anti skipped polyols 112 or 113. A recent total synthesis of macrolactin A by Carreira and co-workers utilizes aldol... 

As with Stille cross-coupling, use of the Suzuki reaction has had a dramatic effect on organic synthesis.137 The chemo-, regio-, and stereoselectivity observed with Suzuki cross-coupling are quite similar to those observed for the Stille reaction. Equations 12.64-12.67 show some of the scope of Suzuki cross-coupling. 

While organic chlorides, bromides, and iodides are still the most common substrates, recently the scope has been expanded to include organic fluorides, nitriles, ethers, triflates, phosphates, iodonium salts, and substrates with various chalconide-leaving groups. Of the different cross-coupling reactions covered in this article, the Kumada Corriu protocol has been the least reviewed. However, the topic has been covered in recent historical treatments. ... 

Unlike other cross-coupling reactions, for which the scope has rapidly expanded in recent years, the range of electrophilic substrates that can be used successfully in the Sonogashira protocol is still rather limited. Vinylic substrates (iodides, bromides, chlorides, triflates, and more recently tosylates) typically yield the best results. For aromatic substrates, iodides and triflates are preferred over bromides, which in turn give far better yields than aryl chlorides. This latter aspect of the reaction is particularly frustrating when one considers the recent advances in the activation of aryl chloride substrates for reactivity in other cross-coupling protocols. ... 

By extension to cross-coupling with vinyl and aryl triflates, the scope of the Stille reaction has been expanded greatly. Almost all functional groups are tolerated without the need for protection. The reactivity order of organic halides is I>Br>OTf>>Cl, but the order between Br and OTf can be reversed by addition of LiCl. By addition of LiCl (2 or 3 equiv) to provide a more reactive Pd-intermediate (vinyl-PdCIl versus vinyl-PdOTfL ) [25] and/or stable tin by-product (RjSnCl versus R3SnOTf), the reaction proceeds smoothly at ambient temperature. 

Good yields are achieved for five- and six-membered ring cyclizations by the intramolecular cross-coupling reaction of haloalkenes [139, 152], but the scope of reaction is still limited by the availability of the haloalkenes, particularly because of the absence of a simple method for preparing cyclic haloalkenes from ketone precursors. The ready availability of triflates from carbonyl compounds now offers a valuable tool for the annulation of ketones (Scheme 2-56) [160]. 

The scope of the Negishi reaction is broad, similar to that of Stille and Suzuki cross-coupling. The reaction seems to work if R = aryl, vinyl, alkynyl, acyl, allyl, benzyl, homoallyl (-CH2-CH2-CH=CH2) and homobenzyl (-CH2-CH2-Ph), or even primary alkyl, and if X = I, Br, or OTf (Cl works, but often sluggishly). Correspondingly, R = aryl, vinyl, alkynyl, allyl, benzyl, and primary alkyl. The organozinc reagent may either be used as a preformed compound, such as R2Zn... 

In this variation of the Pd-catalyzed cross-coupling reaction, which is closely related to the Stephen-Castro reaction, copper acetylides are reacted with (hetero)aryl halides or triflates to produce (hetero)aryl alkynes [111]. The Sonogashira reaction is comparable to the Suzuki or Stille reactions in its scope and functional group tolerability. 

Scope and limitations of the Heck reaction synthesis of dienes The Heck reaction with electron-rich alkenes A synthesis of strychnine Recent developments in the Heck reaction Sp2-sp2 Cross-Coupling Reactions by Transmetallation Stille coupling... 

Cross-couplings. The Stille coupling of organostannanes with hypervalent iodine compounds has a broad scope. Diaryl and dialkenyl tellurides are also active toward alkenes if the catalytic system contains AgOAc. ... 

The cross-coupling reactions of aryl- and alkenylsilanols are adequate replacements for the analogous Stille and Suzuki reactions. Yet the scope of organosilanol coupHng extends beyond this. It has also been shown that the use of alkynylsilanols presents a viable alternative to the classic Sonogoshira-type couphngs of alkynes. 

Nucleophilic attack on Pd-bound ligands, be they a, tt, or (t-tt, provides an assortment of excellent methods for the formation of carbon-carbon and carbon-heteroatom bonds, as represented by general transformations shown in Scheme 1. In particular, these processes have provided three major methods for the formation of the carbon-heteroatom bonds, and they have extensively been applied to the synthesis of natural products. More recently, the Pd-catalyzed cross-coupling has also been developed so as to be applicable to the formation of C— N, C—O, and other carbon-heteroatom bonds, as discussed in Sect. III.3, even though the current scope of their application to natural product synthesis is still rather limited. 

---