Categories: Synthesis of O-Heterocycles > Lactones >
Synthesis of 5,6-dihydropyran-2-ones
Recent Literature
A Cu(I)-catalyzed direct vinylogous aldol reaction (DVAR) of β,γ-unsaturated
esters and various aldehydes enables a synthesis of chiral α,β-unsaturated
δ-lactones. For aromatic aldehydes, a one-pot reaction consisting of DVAR,
isomerization of the unsaturated carbon-carbon double bond, and subsequent
intramolecular transesterification was required, whereas for α,β-unsaturated and
aliphatic aldehydes, the reaction proceeded directly.
H.-J. Zhang, L. Yin, J. Am. Chem. Soc.,
2018,
140, 12270-12279.
The synthesis of α,β-unsaturated lactones from β-acetoxy aldehydes is
achieved by reaction with the lithium enolate of methyl acetate. The reaction is
relatively insensitive to structural changes in the aldehyde substrates. The
process was extended to the synthesis of five-ring lactones from α-acetoxy
aldehydes.
G. E. Keck, X.-Y. Li, C. E. Knutson,
Org. Lett., 1999, 1, 411-413.
Highly stereoselective 2-oxonia-Cope rearrangement reactions between
rationally designed nonracemic vinylogous aldolation synthons and aldehydes
provide δ-hydroxy-α,β-unsaturated esters with excellent enantioselectivities and
unprecedented Z- and E-selectivities.
A. Padarti, H. Han, Org. Lett.,
2018, 20, 1448-1452.
1-Alkoxy-1-amino-1,3-butadienes undergo Diels-Alder (DA) and
hetero-Diels-Alder (HDA) reactions under mild reaction conditions with a variety
of electron-deficient dienophiles. The hydrolysis of the DA cycloadducts
provides 6-substituted and 6,6-disubstituted 2-cylohexenones in good yields with
excellent regioselectivities, whereas HDA cycloadducts afford 6-substituted
5,6-dihydropyran-2-ones.
P. K. Elkin, N. D. Durfee, V. H. Rawal, Org. Lett., 2021, 23,
5288-5293.
An AgOTf-catalyzed intramolecular cyclization of phenoxyethynyl diols affords
multisubstituted α,β-unsaturated-γ-lactones in good yields under mild conditions.
This method was also applicable to the synthesis of α,β-unsaturated-δ-lactones.
Replacement of AgOTf with a stoichiometric amount of N-bromosuccinimide
furnishes α-bromo-substituted α,β-unsaturated lactones.
M. Egi, Y. Ota, Y. Nishimura, K. Shimizu, K. Azechi, S. Akai, Org. Lett., 2013,
15, 4150-4153.
Highly functionalized δ-lactones were produced in the presence of a catalytic
amount of the Cu(OAc)2-DIFLUORPHOS complex through three-component assembly of
dialkylzincs, allenic esters, and unactivated ketones. This CAMCR (catalytic
asymmetric multicomponent reaction) constructs two C-C bonds and one
tetrasubstituted chiral center simultaneously.
K. Oisaki, D. Zhao, M. Kanai, M. Shibasaki, J. Am. Chem. Soc., 2007,
129, 7439-7443.
In a construction of 6-substituted 3-fluoro-5,6-dihydropyran-2-ones under mild
conditions, the key step is a Julia-Kocienski olefination.
S. K. Mandal, A. Sarkar, P. Chakraborty, A. P. Chattoapdhyay,
Synlett, 2018, 29, 75-78.
A mild, enantioselective
hetero-Diels-Alder (HDA) reaction of the Brassard diene with aldehydes in the
presence of a chiral titanium(IV) tridentate Schiff-base complexe has been
developed. The
mechanism is discussed.
Q. Fan, L. Lin, J. Liu, Y. Huang, X. Feng, Eur. J. Org. Chem., 2005,
3542-3552.