Ene reactions of allylic tin compounds with singlet oxygen and with 4-phenyl-1,2,4-triazoline-3,5-dione

Abstract

Allylic tin compounds (I) react with singlet oxygen to give allylperoxystannyl compounds (11) by stannylallylation, stannylallyl hydroperoxides (111) by hydroallylation, and 4-stannyl-l,2-dioxolanes (IV) by rearrangement and cycloaddition. For example, 3-trimethylstannylprop-1 -ene (I; R = R' = H; I II 111 IV M = Me,Sn) in CH,CI, at room temperature gives 25% II, 25% 111 and 50% IV; 1 -tributylstannylcyclohex-2-ene (I; R-R' = -CH,CH,CH,-; M = Bu,Sn) in CH,CI, gives 66% II and 33% IV, but in MeOH-benzene, the yield of II is >95%. The dioxolane IV appears to be a primary product of the reaction, and does not result from ring-closure of 11. Under similar conditions, triethylsilylcyclohex-2-ene (I; R-R' = -CH,CH,CH,-;M = Et,Si) in CH,CI, shows only the hydroallylation reaction t o give II. Similar reactions occur with 4-phenyl-l,3,4-triazoline-2,5-dione. For example, 3-trimethylstannylprop-1 -ene in CH,CI, gives 85% V and 15% VII, but in MeOH-benzene, the yield of V is 95%. Under I V VI VIIthe same conditions, triethylsilylcyclohex-2-ene gives 5% V, 70% VI, and 25% of the cycloadduct VII.These reactions are discussed in terms of the usual mechanistic models for the ene reactions, and for the p-effect of organometallic groups.

Tin

“…Allyl-and benzyltin compounds can also be prepared f r o m the reagents produced by superbase metallation of alkenes or alkylbenzenes. 40 ' 41 Alkynyltin compounds can also be prepared by treating the alkyne and tin tetrachloride with a tertiary amine in dichloromethane; tetra(phenylethynyl)tin has been isolated f r o m this reaction, and the intermediate compounds (PhC=C) n SnCl 4 _ n (n = 1-3) have been detected by NMR spectroscopy. In the presence o f a n aldehyde or acetal or enone, the alkynyltin compound reacts in situ to give the appropriate product (Equation (II)).…”

“…I f Bu 3 Sn-TMS is treated with tetrabutylammonium chloride, caesium fluoride or tris(diethylamino)sulfonium difluorotrimethyl silicate ((Et 2 N) 3 S + TMS-F 2 ", tasf) in DMF, the trimethylstannyl anion is formed, and will take part in the usual reactions which are recognized for the alkali metal derivatives R 3 SnM. An example is shown in Equation (189) (189) No catenary compound with all the group 1 4 elements (C-Si-Ge-Sn-Pb) has yet been reported, but four of the five elements have been joined in the compounds Me 3 CSiMe 2 GeMe2SnMe3 and Me 3 CSiMe 2 GeMe2SnPh 3 . The former compound is a thermally stable liquid, but the latter is a crystalline solid, which by x-ray diffraction shows a normal germanium-tin bond length of 0.2609(1) nm.…”

A formal [3+2] cycloaddition for the synthesis of bicyclo[3.2.1]octanes

“…The successful approach involved metallation of cyclohexene 1 with Schlosser's base 16,17 , followed by silylation with triisopropylsilyl chloride to provide 2a 18 in 90% yield. This facile and high yielding route also worked well for the preparation of allylsilane 2b 19 that was obtained in 83% yield.…”

Ene reactions of allylic derivatives of silicon, germanium, tin and lead with N-phenyltriazolinedione: the effect of varying the metal

“…(2)] which can then undergo pericyclic transfer of the metal [eqn. (3)], or of hydrogen [eqn. (4)] or a [1,2] shift of the metal with accompanying ring closure [eqn.…”

“…centre became more electropositive, the proportion of the Mene reaction [reaction (3)] increased, and, with a suitable choice of ligands, this could be caused to be the exclusive reaction.…”