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d 5 ‐Reactions of Doubly Deprotonated γ,δ‐Unsaturated Carbonyl Derivatives with Electrophiles. A Novel Approach to the Synthesis of Tetrahydrofuran and Tetrahydropyran Derivatives
Author(s) -
Seebach Dieter,
Pohmakotr Manat,
Schregenberger Christian,
Weidmann Beat,
Mali Raghao S.,
Pohmakotr Srisuke
Publication year - 1982
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19820650202
Subject(s) - chemistry , electrophile , tetrahydropyran , ketone , synthon , tetrahydrofuran , aldehyde , reagent , ketene , medicinal chemistry , organic chemistry , epoxide , acetyl chloride , silylation , catalysis , ring (chemistry) , solvent
The dienone‐dianion derivatives 1 react with all types of electrophiles tested (alkyl halide, silyl chloride, ester, ketone, aldehyde, epoxide) to give β, γ‐unsaturated carbonyl compounds of type A (see Formulae 2 – 6 , 13 , 14 and Tables 1–5 ). The α‐ and β‐hydroxyalkylation products obtained from 1a – 1d can be converted to tetra‐hydrofuran and tetrahydropyran derivatives 7 and 16 , respectively ( Tables 1 and 2 ), those from the sulfur analogues 1e and 1f to ketene thioacetals 9 and to dienone derivatives 10 and 12. The t ‐butyl and α‐hydroxy‐ketones are cleaved to give nitriles, amides, carboxylic acids and esters ( Formulae 16 ‐ 25 ). The reagents 1 allow to synthesize products with distant functional groups in one step ( cf. 1,8‐diketones 14 and Formulae 26 – 30 ); they correspond to the d 5 ‐synthons 31 – 33 ; in Table 6, they are compared with other d 5 ‐reagents.