Diels-Alder reactions 2-trimethylsilylmethyl-1,3-butadiene

Table 3 Diels-Alder Reactions of Isoprene, 2-Trimethylsilylmethyl- and 2-Ttimethylstannylmethyl-1,3-butadienes with Conjugated Enoyl Compounds (Scheme 43)...

Diels-Alder Reactions. 2-Trimethylsilylmethyl-1,2-butadiene and 2-trimethylstannylmethyl-1,3-butadiene undergo facile cycloaddition with dienophiles (eq 11). The reactions of 2-trimethylsilylmethyl- and 2-trimethylstannylmethyl-1,3-butadiene with unsymmetrical dienophiles give the so-called para product predominantly, and the selectivity is much higher in the reactions with 2-trimethylsilylmethyl- and 2-trimethylstarmylmethyl-1,3-butadiene compared to reactions with isoprene. The paralmeta ratios in the reactions with methyl acrylate (eq 12) are 70/30 (X = H), 84/16 (X = SiMej), and 91/9 (X = SnMes)."... 

Trimethylsilylmethyl-1,3-butadiene undergoes highly re-gioselective aluminum chloride-catalyzed Diels-Alder reactions with dienophiles such as acrolein and methyl vinyl ketone in which the "para isomers are obtained almost exclusively (eqs 13 and 14). The adducts are converted readily to a variety of naturally occurring mono- and sesquiterpenes (eq 15). ... 

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