New Ethylzinc Reagents with Remarkable Properties in Palladium-Catalyzed Zinc-Ene Reactions

Article Article scientifique Article New Ethylzinc Reagents with Remarkable Properties in Palladium-Catalyzed Zinc-Ene Reactions eng 1997 author Von Oppolzer Wolfgang 25270 author Schroeder Fridtjof Harmen 29522 author Kahl Sonke 100375 2047-2057 10.1002/hlca.19970800705 0018-019X http://doi.wiley.com/10.1002/hlca.19970800705 Pd‐Catalyzed Zn‐ene allylic olefinations with the new ethylzinc reagents Et-Zn-OSO₂CF3 (4) and Et-Zn-OC(O)CF(MeO)CF₃ (5) in CH₂Cl₂ showed an unexpected trans‐selectivity in the ring closure to cyclopentane derivatives (see Scheme 2 and Table 1). This strong trans‐selectivity is in contrast with the corresponding known Zn‐ene reaction using Et₂Zn in Et₂O which shows a high cis‐selectivity (Table 1). The probable radical origin of the observed trans‐selectivity is discussed. The Zn‐ene reaction products of the type R-Zn-OSO₂CF₃ could be derivatized by the known protonation, iodination, and cyanation yielding 8–10 (Scheme 4 and Table 2), these derivatizations could furthermore be extended by allylation and oxidation reaction (→ 13, 15, and 16; see Scheme 5). Dewey 540 36 Département de chimie organique 141 false Helvetica Chimica Acta 80 7 df57767f-09ed-4417-9228-e86b33a9098d Article (Published version) Restricted Oppolzer_et_al-1997-Helvetica_Chimica_Acta-2.pdf 706492 application/pdf restrictedAccess Faculté des sciences / Section de chimie et biochimie / Département de chimie organique

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New Ethylzinc Reagents with Remarkable Properties in Palladium-Catalyzed Zinc-Ene Reactions	Helvetica Chimica Acta			1997	277	0

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Kahl, Sonke