Stannylated derivatives

Stannyl derivatives of 2ff-pyran-2-one, accessible from bromopyranones by cross coupling with organotin reagents, themselves take part in Pd(0)-catalyscd cross coupling with enol triflates. This methodology offers a new approach to steroidal pyran-2-ones <96JOC6693>. 

Typical NMR data were compiled in CHEC-II(1996) <1996CHEC-II(8)2> for 3.77-pyrrolizine 1, its lithium salt, the pyrrolizin-3-one 2, and its regioisomer (pyrrolizin-2-one). More recently, Kissounko et al. <1998JOM(556)145> reported the H chemical shifts of the parent pyrrolizine anion and anion 21a as well as those of their silylated or stannylated derivatives 22-26. 

Alk-2- and alk-3-ynoic acids are stannylated with Bu3Sn(Bu)CuCNLi2 to give the 3- and 4-stannyl derivatives, respectively, but the tributylstannyl ester of but-3-ynoic acid gives the reverse regioselectivity (Equations (30) and (31)).115... 

The stannyl derivatives of the higher boranes have been reviewed, this field. 

The iodo benzamide derivative of pyrrolo[2,l-c][l,4]benzodiazepine 367 (R = I, Scheme 75, Section 5.1.1) reacts with bis(tributyl)tin, lithium chloride and tetrakis(triphenylphosphine) palladium(O) in refluxing dioxane to yield the stannyl derivative 370. The latter couples with substituted aryl bromides in the presence of... 

The first efficient Stille coupling of heteroaiomatic cations to tributyl stannyl derivatives has been reported. 2-Tributylstannylthiazole 21 was coupled with the btomoquinolizinimn salt 28, in the presence of Pd(0) / Cul catalysis, to afford the quinolizinium salt 29 in moderate yield. This method provides a good alternative to nucleophilic substitution of quinoliziniiun derivatives, which are usually very unstable in the presence nucleophilic species <990L545>. 

This work on organometallic resists was extended by MacDonald et al. (126) to include poly(trimethylstannylstyrene) and poly(trimethylsilylstyrene) together with copolymers of these materials with p-chlorostyrene. The sensitivity of the stannyl derivative to electrons is reported to be 0.5 / 2, and the copolymer with p-chlorostyrene could be patterned in the deep UV at a dose of 10 mJ/cm2 at 254 nm. The materials show excellent oxygen RIE resistance due to the formation of involatile oxides of the metals on the surface of the pattern. 

C-ONs distance in 185 and 186 was not significantly different from the cij-stannyl derivative 187 or the 4-terf-butyl derivative 166. 

The first alkynyliodonium salt, (phenylethynyl)phenyliodonium chloride, synthesized in low yields from (dichloroiodo)benzene (3) and lithium phenylacetylide (equation 1), was reported in 196526. This chloride salt is unstable and readily decomposes to a 1 1 mixture of chloro(phenyl)acetylene and iodobenzene. It was not until the 1980s, however, that alkynyliodonium salts became generally available. This was made possible by the introduction of sulfonyloxy-/l3-iodanes as synthetic reagents46 and by the recognition that iodosylbenzene (4) can be activated either with boron trifluoride etherate or with triethy-loxonium tetrafluoroborate31. These reagents are now widely employed for the conversion of terminal alkynes and their 1-silyl and 1-stannyl derivatives to alkynyliodonium salts (equations 2 and 3). A more exhaustive survey of iodine(III) reagents that have been... 

The indole 836, the product of -substitution in the Stille reaction of the 3-iodoindole 834 with the trimethyl-stannyl derivative of imidazole 835, was obtained as shown in Equation 211 <1998H(48)11>. 

In the electrochemical oxidation, similar reaction was observed (Scheme 12). Cation radical CR26 generated by electrochemical oxidation of a-stannyl sulfides cleaves to give carbocation C26, which react with allyltrimethylsilane or the silyl enol ether of cyclohexanone to give the usual addition products. In this electrochemical reaction, stannyl derivatives also afforded the desired product 27 or 28 in better yield compared with the corresponding silyl derivatives. 

During the above study, it became apparent that stannyl amides exhibit lower oxidation potential compared with the original nonstan-nylated amides. These phenomena have also been reported by Yoshida et al. in their measurements of oxidation potentials of a-stannyl derivatives (Table 7). Yoshida and co-workers explained that the decrease in the oxidation potential is attributed to the rise of the HOMO level of the stannyl (or silyl) compound by interaction of the carbon-tin (or carbon-silicon) a bond and the nonbonding p orbital of the oxygen atom. 

Selective silyllstannyl exchange. Regioselective aldol condensation of methyl ketones can be effected by generation of the a-stannyl derivative via silyl-stannyl exchange... 

Addition of catalytic or stoichiometric quantities of CuCN (TiCl)2 radically increases the reactivity of diorganozinc (R2Zn) and organozinc halide (RZnX) compounds. The resulting copper-zinc species (RCu(CN)ZnR or RCu(CN)ZnX) react with staimyl chlorides (RjSnCl) to give the corresponding alkylated stannyl derivatives (RjSnR)... 

Silyl, Germyl, and Stannyl Derivatives of Azenes, N Hn Part //. Derivatives of Triazene N3H3, Tetrazene N4H4, and Pentazene N5H5 ... 

The purpose of this article is to summarize the preparation and properties of silyl, germyl, and stannyl derivatives of azenes N H (n = 2-5). This part II of the review deals with known Group IV derivatives of triazene, tetrazene, and pentazene (n = 3-5 excluding purely organic substituted triazenes and tetrazenes, cf. refs 2,3). Group IV derivatives of diazene were discussed in Part I of the review (1). 

Some physical properties of silyl, germyl, and stannyl derivatives of triazene or organyltriazenes that have been isolated to date, along with their methods of preparation, are listed in Table I. In general, triazenes can be categorized into five types (18a-18e) of triazenes or organyl-... 

SiLYL, Germyl, and Stannyl Derivatives ofTriazene (N3H3) and Organyltriazenes... 

Recent Developments in Theoretical Organometallic Chemistry. 15, I Redistribution Equilibria of Organometallic Compounds, 6, 171 Redistribution Reactions of Transition Metal Organometallic Complexes, 23, 9S Redistribution Reactions on Silicon Catalyzed by Transition Metal Complexes, 19, 213 Remarkable Features of (7] -Conjugated Diene) zirconocene and -hafnocene Complexes, 24, I Selectivity Control in Nickel-Catalyzed Olefln Oligomerization, 17, lOS Silyl. Germyl, and Stannyl Derivatives of Azenes. N H Part I. Derivatives of Diazene, N,H2, 23, 131... 

Several reactions were also carried out from the major stannyl derivative 7f (Scheme 4). The major adducts were the same as in the direct alkylation of 5a. 

Michael addition of trialkylstannyllithium to cyclohexenone SAMP- or RAMP-hydrazone gives 3-stannyl derivatives with de values of 42-44%, while subsequent alkylation of the enolate formed affords trans-products with de values >96%. The hydrazones obtained are subjected to ozonolysis to give 3-stannylcyclohexanones trans-1 with ee values up to 96%17. 

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