Categories: Synthesis of O-Heterocycles, C-O Bond Formation >
Synthesis of lactols and related compounds
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Protecting Groups
Recent Literature
A mild, gold- and brønstedt acid-catalyzed tandem
cycloisomerization-hydroalkoxylation of various homopropargylic alcohols in the
presence of an alcohol provides an efficient route to tetrahydrofuranyl ethers.
V. Belting, N. Krause, Org. Lett.,
2006, 8, 4489-4492.
The reaction of arenediazonium tetrafluoroborates with THP-protected (Z)-2-butene-1,4-diol
in the presence of Pd(OAc)2 in MeOH at 35˚C gives
4-aryl-2-methoxytetrahydrofurans in good yields. The reaction tolerates
various functional groups including ester, keto, cyano, nitro, chloro, and bromo
functionalities as well as ortho substituents. Oxidation with MCPBA gives
γ-aryl-β-butyrolactone derivatives.
S. Cacchi, G. Fabrizi, A. Goggiamani, A. Sferrazza, Synlett, 2009,
973-977.
C(sp3)-H dehydrogenative cross-couplings of ethers,
tetrahydrothiophenes, and pyrrolidines with alcohols were achieved under visible
light irradiation by using iodobenzene and an in situ-formed gold complex. This
method offers broad functional group compatibility and was successfully applied
in late-stage modifications of bioactive molecules.
X. Si, L. Zhang, Z. Wu, M. Rudolph, A. M. Asiri, A. S. K. Hashmi,
Org. Lett., 2020, 22, 5844-5849.
An iron-catalyzed α-C(sp3)-H activation of cyclic and acyclic ethers provides
an efficient and green method for the synthesis of mixed acetals in very good
yields. The robustness of this protocol is demonstrated by the late-stage
oxidation of a structurally complex natural product.
W. Han, L. Cheng, H. Zhao, Synlett, 2020,
31,
1400-1403.
Lipase B from Candida antarctica catalyzes the oxidative ring expansion of
furfuryl alcohols in the presence of aqueous hydrogen peroxide to yield
functionalized pyranones under mild conditions. The corresponding piperidinone
derivatives can be obtained by a similar enzymatic rearrangement of N-protected
furfurylamines.
F. Blume, P. Sprengart, J. Deska,
Synlett, 2018, 29, 1293-1296.
The use of CuCl and NaBH4 enables an efficient, one-pot method for
the highly chemoselective synthesis of δ-lactols from α,β-unsaturated δ-lactones
in methanol.
Y. Matsumoto, M. Yonaga,
Synlett, 2014, 25, 1764-1768.
Copper catalyzes a mild acetalization of boronic esters in the presence of a
variety of functional groups. This Chan-Lam coupling method enables an
orthogonal acetalization of substrates with reactive, acid-sensitive functional
groups.
E. M. Miller, M. A. Walczak, J. Org. Chem., 2020, 85,
8230-8239.
Hg(II) salts are highly efficient catalysts for a versatile construction of
spiroketals in an instant reaction in high yields at ambient temperature from
alkyne diols or THP-semiprotected alkyne diols in aqueous conditions.
Monounsaturated spiroketals and furans were accessed with equal ease when
propargylic triols (or propargylic diols) were subjected to similar conditions.
K. Ravindar, M. S. Reddy, P. Deslongchamps, Org. Lett., 2011,
13, 3178-3181.
K. Ravindar, M. S. Reddy, P. Deslongchamps, Org. Lett., 2011,
13, 3178-3181.
An intramolecular hydro-O-alkylation of aldehydes leads to spiroketals, bicyclic ketals, and aminals.
Tertiary and sterically hindered secondary sp3 C-H bonds are
transformed into C-O bonds under the action of a catalytic amount of a variety of
Lewis acids. The mechanism probably involves a tandem hydride transfer/cyclization sequence.
S. J. Pastine, D. Sames, Org. Lett.,
2005,
7, 5429-5431.
A cyclization of monopropargylic triols to form olefin-containing spiroketals is
rapid and high yielding in the presence of 2 mol % of a catalyst generated in
situ from Au[P(t-Bu)2(o-biphenyl)]Cl and AgOTf. Various
substituted triols lead to substituted 5- and 6-membered ring spiroketals.
A. Aponick, C.-Y. Li, J. A. Palmes, Org. Lett., 2009,
11, 121-124.
