of KDN
Simple thought it appears, there has not been a good protocol for opening an
epoxide 1 with a stabilized enolate. Ferdinando Pizzo of the Università di
Perugia developed
(Tetrahedron Lett. 2010, 51, 1566.
DOI: 10.1016/j.tetlet.2010.01.055)
a solution to this problem. 1803603-34-0 Price Masahiro Terada of Tohoku University found
(Angew. Chem. Int. Ed. 2010, 49, 1858.
DOI: 10.1002/anie.200906647)
that under organocatalysis, the prochiral 4 condensed
with aromatic aldehydes with high relative and absolute stereocontrol.
Jon T. Njardarson, now at the University of Arizona, showed
(Angew. PMID:23319057 Chem. Int. Buy288617-75-4 Ed. 2010, 49, 1648.
DOI: 10.1002/anie.200906830)
that the geometry of the epoxide 7 dictated the relative
configuration of the product dihydrofuran 8.
John P. Wolfe of the University of Michigan devised
(Org. Lett. 2010, 12, 1268.
DOI: 10.1021/ol1001472)
conditions for the diastereocontrolled cyclization of 9 to 10.
Robert Britton of Simon Fraser University observed
(Org. Lett. 2010, 12, 1716.
DOI: 10.1021/ol100260z)
that the microwave-induced closure of 12 proceeded with clean inversion.
Christian B. W. Stark of the Universität Leipzig established
(Angew. Chem. Int. Ed. 2010, 49, 1587.
DOI: 10.1002/anie.200903090)
that the Ru-mediated oxidative cyclization of 14 to 15 was also highly
diastereocontrolled.
Two all-trans diastereomers could emerge from the cascade aldol condensation
of 16 with an aldehyde. Takashi Yamazaki of the Tokyo University of
Agriculture and Technology devised
(Org. Lett. 2010, 12, 268.
DOI: 10.1021/ol902592t)
conditions for the selective preparation of either diastereomer. Xuegong
She of Lanzhou University uncovered
(J. Am. Chem. Soc. 2010, 132, 1788.
DOI: 10.1021/ja910346m)
conditions for the Pt-mediated cyclization of the simple
substrate 18 to the
tetrahydropyran 19.
Michael J. Zacuto of Merck Process established
(Org. Lett. 2010, 12, 684.
DOI: 10.1021/ol9026667)
the Ru-catalyzed cyclization of 20 to 21. When an
OH was not available, NH insertion was also efficient. Fabien Gagosz of the
Ecole Polytechnique Palaiseau devised
(J. Am. Chem. Soc. 2010, 132, 3543.
DOI: 10.1021/ja9100134)
the mechanistically-distinct Au-mediated cyclization of 22 to 23.
Glenn C. Micalizio of Scripps/Florida used
(J. Am. Chem. Soc. 2010, 132, 7602.
DOI: 10.1021/ja102888f)
the protocol he had developed to couple 24 and 25
to give a intermediate trisubstituted alkene.
Oxidative cleavage of the alkene delivered the ketone, that under acidic conditions cyclized to the spiroketal
26. Kaori Ando of Gifu University extended
(Org. Lett. 2010, 11, 1460.
DOI: 10.1021/ol100071d)
the Z-selective
Horner-Emmons condensation to macrolide
construction, cyclizing 27 to 28.
Peter H. Seeberger, now at the Max-Planck-Institute Potsdam, and Donald
Hilvert of ETH Zurich deployed
(Nat. Chem. 2010, 2, 102.
DOI: 10.1038/nchem.504)
the promiscuous aldolase macrophomate synthase to add 30 to 29, to
give, after deprotection, the valuable higher sugar KDN (31). Over a wide
range of α-chiral aldehydes, the addition of 30 was efficient, and proceeded to
give the same absolute configuration of the newly-established stereogenic center.
