title: Nazarov cyclization of divinyl ketones bearing an ester group at the β-position: a remarkable effect of α-substitution and alkene geometry on regioselectivity.
abstract: The Nazarov cyclization of divinyl ketones with an ester at the β-position was examined with particular reference to where the cyclic double bond forms. We observed unprecedented regioselectivity, dictated by the subtle substitution patterns at the α-position and alkene geometry of α,β and mostly, this selectivity is regardless of substitutions at α'- and β'-positions. The major implications of these observations are an aromatic group at the α-position with E-olefin geometry provides a cyclopentenone in which the double bond is not in conjugation with an ester, whereas Z-olefin provides a cyclopentenone in which the double bond is in conjugation with an ester; and divinyl ketones bearing an ester group at the β-position and an alkyl group at the α-position with E-olefin geometry provide a cyclopentenone in which the double bond is in conjugation with the ester.
authors: CPC (Organic Chemistry-II) Division, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad-500007, India. gsudhakar@iict.res.in and Academy of Scientific and Innovative Research, New Delhi, India.
authors: Gangarajula
authors: G
authors: Sudhakar
authors: CPC (Organic Chemistry-II) Division, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad-500007, India. gsudhakar@iict.res.in and Academy of Scientific and Innovative Research, New Delhi, India.
authors: Jakka
authors: J
authors: Raghavaiah
authors: CPC (Organic Chemistry-II) Division, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad-500007, India. gsudhakar@iict.res.in.
authors: Gaddam
authors: G
authors: Mahesh
authors: Centre for NMR and Structural Chemistry, CSIR-IICT, Hyderabad-500007, India.
authors: Kiran Kumar
authors: KK
authors: Singarapu