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Halostannanes

Another major route for synthesis of stannanes is reaction of an organometallic reagent with a trisubstituted halostannane, which is the normal route for the preparation of aryl stannanes. [Pg.834]

The halostannanes can also be generated in situ by reactions of allylic halides with tin metal or stannous halides. [Pg.839]

Reactions of tetraallylstannanes with aldehydes catalyzed by SnCl4 also appear to involve a halostannane intermediate. It can be demonstrated by NMR that there is a rapid redistribution of the allyl group.174 Reactions with these halostannanes are believed to proceed through a cyclic TS. [Pg.841]

X Attempted direct aminolysis of halostannanes yielded the corresponding amine adducts.2... [Pg.137]

It is the purpose of this chapter to summarize what is currently known about the stereochemistry and conformation of organogermanium, tin and lead compounds. Coverage is selective rather than exhaustive. The first section deals with compounds in which substitution by four different groups causes the metal atom to be stereogenic. We have limited our discussion to those cases in which at least three of the four substituents are alkyl or aryl. In this section we also briefly discuss pentacoordinated triorgano halostannanes. [Pg.196]

A series of nonracemic triorganotin hydrides (37-39) was prepared by reduction of racemic halostannane precursors with a chiral alkoxy hydride reagent (Scheme 14)21. [Pg.208]

As expected, both trans analogues 63 and 64 of stannanes 61 and 62 adopt the chair e/a conformation. The halostannane 64 shows no tendency toward intra- or intermolecular association. [Pg.226]

Crotonic esters and certain homologues, when converted to their enolates with LDA and treated with stannyl and germyl chlorides, afford the y-metallo derivatives (Table 10)57. In contrast, silylation of these enolates leads to the 0-silyl derivatives. Interestingly, the halostannane derivatives show a strong preference for the (Z) geometry suggestive of a donor-acceptor interaction between the carbonyl oxygen and the electropositive tin atom,... [Pg.227]

Organotin halides are versatile reagents for which many derivatizing schemes can be devised. Trace analysis of organotin componds in environmental samples often involve halostannanes, as was discussed in Section in. [Pg.408]

Halostannanes HsSnX (X = Cl, Br, I) are formed by the action of hydrogen halides on stannane at room temperature302,303. [Pg.514]

Various allylhalostannanes can transfer allyl groups to carbonyl compounds. In this case, the reagent acts both as a Lewis acid and as the source of the nucleophilic allyl group. Reactions with halostannanes are believed to proceed through cyclic transition states. [Pg.580]

In conclusion it should be noted that organometallic synthetic methods of organyl-halostannanes were not as widely used as in the synthesis of the isostructural compounds of silicon and germanium. Section III.E explains the reason for this. [Pg.41]

The first attempts to obtain dialkylstannandiols R2Sn(OH)2 by the hydrolysis of dialkyl-halostannanes were unsuccessful. These compounds turned out to be extremely unstable and they dehydrated immediately to amorphous polyperorganylstannoxane-a, >-diols... [Pg.50]

When Lewis acids such as SnCU and TiCU are used to promote additions of allylic trialkyltin reagents to aldehydes several reaction outcomes are possible, depending on stoichiometry and the mode of addition. If the Lewis acid is added to the aldehyde followed by the allylic stannane, the typical product (syn for crotylstannanes) derived from an acyclic transition state is formed. If, however, the stannane and Lewis acid are premixed and left to equilibrate, metathesis can occur forming the allylic halome-tal compound which reacts with the subsequently added aldehyde to give products (anti for crotyl) consistent with a cyclic transition state (Eq. 22). The initially formed allylic halostannane gives rise to the linear adduct, but if aldehyde addition is delayed, this initial secondary allylic metal halide can equilibrate to the primary isomer which then reacts with the aldehyde to afford the branched product. [Pg.474]

Table 47. In situ addition of propargyiic/allenic halostannanes to aldehydes. Table 47. In situ addition of propargyiic/allenic halostannanes to aldehydes.
Reactions of halostannanes with complex hydrides provide routes to stannanes (Table 1). Complex hydrides most used are MBH. (M = Li, Na, K) and LiAlH. The LiBH and LiAlH, reductions are carried out in aprotic ether solvents (THE, EtjO, monoglyme). Sodium and K hydroborate reactions may be carried out in H O. Most complex hydride reductions are adaptable to Sn — D bond synthesis (see also 1.6.7.1.4). Halostannanes are reduced by LiAlH ... [Pg.226]

Lithium tetrahydroaluminate-d. and LiBD reductions of halostannanes constitute preferred syntheses of deuteriostannanes, e.g. ... [Pg.247]


See other pages where Halostannanes is mentioned: [Pg.838]    [Pg.195]    [Pg.212]    [Pg.226]    [Pg.233]    [Pg.1917]    [Pg.154]    [Pg.53]    [Pg.987]    [Pg.53]    [Pg.987]    [Pg.479]    [Pg.229]    [Pg.230]    [Pg.247]   
See also in sourсe #XX -- [ Pg.154 ]

See also in sourсe #XX -- [ Pg.524 ]




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Additions of Allylic Halostannanes to Aldehydes

Halostannanes reactions

Halostannanes synthesis

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