[19752-27-3] · C21H36Sn · trans-Cinnamyltributylstannane · (MW 398.15)
Alternate Names: trans-cinnamyltributyltin; trans-(3-phenyl-2-propenyl)tributyltin.
Solubility: sol THF, methylene chloride, chloroform.
Preparative Methods: by the coupling reaction of trans-cinnamylmagnesium bromide with Tri-n-butylchlorostannane (10-20%)2,4,5 or trapping of the lithiated derivative of allylbenzene (s-BuLi in cyclohexane/TMEDA/THF) with tributylchlorostannane at -78 °C (90%).6,7
Analysis of Reagent Purity: CH microanalysis; IR (neat)2 2925 (vs), 1637 (s), 1598 (s), 1495 (s), 1463 (s), 1672 (s), 958 (s) cm-1;IR (1% CCl4)4 1635, 956 cm-1; UV (MeOH) l
Handling, Storage, and Precautions: although toxicological properties have been virtually unexplored, they may be extrapolated from those observed for Allyltributylstannane.8 Use in a fume hood.
Phenylallylation reactions can be realized under Lewis-acid catalysis in a similar manner as those observed using allyltributyl- or Allyltriphenylstannane.1 However, the regiochemistry of phenylallyl addition depends upon the nature of the reaction and the structure of the electrophile substrate used. For example, treatment of trans-cinnamyltributyltin with 2,3-dimethylbenzoquinone in the presence of Boron Trifluoride Etherate results in the exclusive allylation at the a-carbon (eq 1).2 In contrast, a similar reaction with 2,6-dimethylbenzoquinone provides a mixture of a- (49%) and g-adducts (32%) at C-3 of the starting benzoquinone.2
trans-Cinnamyltributyltin undergoes a BF3.OEt2-mediated addition reaction with aldehydes (eq 2)7 as other allyltins (see Allyltributylstannane).1 Interestingly, however, the stereochemical outcome of this reaction is opposite to the syn selectivity encountered for the reactions involving Crotyltributylstannane, where the reactions are postulated to proceed through extended transition states.1,9 The observed anti selectivity of the reaction of trans-cinnamyltributyltin has been speculated to proceed through a cyclic transition state, presumably owing to a greater ionic contribution from the C-Sn bond compared with other allyl- or g-alkylallyltins.7
A novel, highly stereoselective [3 + 2] cycloaddition has been developed between allyltins such as trans-cinnamyltributyltin and a,b-unsaturated acyliron complexes (eq 3).3
The University of Michigan, Ann Arbor, MI, USA