Diastereoselective stereodivergent addition of E- and Z-crotylsilanes to 2-cyclopentenone derivatives with chiral auxiliaries at 2-position

Stereochemical Control in Organic Synthesis Using Silicon-Containing Compounds

“…The relative stereochemistry is not easily explained as being a consequence of an antiperiplanar transition structure, since that explanation works best when the ( Z )- and ( E )-allylsilanes give the same relative stereochemistry. Whatever the explanation, reactions of this type have been used in syntheses of neonepetalactone, nootkatone, juvabione and its epimer, and the steroidal CD ring system 219 …”

“…Whatever the explanation, reactions of this type have been used in syntheses of neonepetalactone, 553 nootkatone, 410 juvabione and its epimer, 554 and the steroidal CD ring system. 555 The allylsilane 821, in spite of being a mixture of E and Z isomers, is remarkable in giving mainly one diastereoisomer 873, just as it was in its reaction with an aldehyde (Scheme 206), not only by being selectively syn with respect to the 1,2-relationship, possibly from an antiperiplanar transition structure making it independent of the geometry of the allylsilane, but also anti with respect to the 1,4 relationship (Scheme 220). 556…”

Catalytic Enantioselective Inverse Electron Demand Hetero‐Diels–Alder Reaction with Allylsilanes

“…Allyltriphenylsilane would approach the Cβ‐ Si face of 2 a via the endo transition state to give cis adducts as major products. The predominance of endo transition state can be explained in terms of a secondary orbital interaction between the allylsilane HOMO and the β,γ‐unsaturated α‐ketoester LUMO15, 16 (Figure 2 a). Indeed, an achiral copper(II) catalyst also preferentially gave cis ‐ 3 a (ca.…”

Catalytic Enantioselective Inverse Electron Demand Hetero‐Diels–Alder Reaction with Allylsilanes

“…Allyltriphenylsilane would approach the Cb-Si face of 2 a via the endo transition state to give cis adducts as major products. The predominance of endo transition state can be explained in terms of a secondary orbital interaction between the allylsilane HOMO and the b,g-unsaturated a-ketoester LUMO [15,16] (Figure 2 a). Indeed, an achiral copper(II) catalyst also preferentially gave cis-3 a (ca.…”