505-03-3Relevant articles and documents
Borane-mediated aldol cycloreduction of monoenone monoketones: Diastereoselective formation of quaternary centers
Huddleston, Ryan R.,Cauble, David F.,Krische, Michael J.
, p. 11 - 14 (2003)
Exposure of monoenone monoketones to catecholborane in THF at ambient temperature results in tandem 1,4-reduction-aldol cyclization. For aromatic and heteroaromatic enones, six-membered cyclic aldol products are formed in excellent yield with high levels of syn diastereoselectivity. Five-membered ring formation proceeds less readily, but the yield of cyclized product is improved through introduction of Rh(I) salts.
Rhodium-Catalyzed Asymmetric Conjugate Alkynylation/Aldol Cyclization Cascade for the Formation of α-Propargyl-β-hydroxyketones
Choo, Ken-Loon,Lautens, Mark
, p. 1380 - 1383 (2018/03/09)
A rhodium-catalyzed conjugate alkynylation/aldol cyclization cascade was developed. Densely functionalized cyclic α-propargyl-β-hydroxyketones were synthesized with simultaneous formation of a C(sp)-C(sp3) bond, a C(sp3)-C(sp3) bond, as well as three new contiguous stereocenters. The transformation was achieved with excellent enantio- and diastereoselectivities using BINAP as the ligand. The synthetic utility of the newly installed alkynyl moiety was exhibited by subjecting the products to an array of derivatizations.
Transaminase Triggered Aza-Michael Approach for the Enantioselective Synthesis of Piperidine Scaffolds
Ryan, James,?iau?iulis, Mindaugas,Gomm, Andrew,Maciá, Beatriz,O’Reilly, Elaine,Caprio, Vittorio
supporting information, p. 15798 - 15800 (2016/12/22)
The expanding “toolbox” of biocatalysts opens new opportunities to redesign synthetic strategies to target molecules by incorporating a key enzymatic step into the synthesis. Herein, we describe a general biocatalytic approach for the enantioselective preparation of 2,6-disubstituted piperidines starting from easily accessible pro-chiral ketoenones. The strategy represents a new biocatalytic disconnection, which relies on an ω-TA-mediated aza-Michael reaction. Significantly, we show that the reversible enzymatic process can power the shuttling of amine functionality across a molecular framework, providing access to the desired aza-Michael products.
Efficient and Selective Cu/Nitroxyl-Catalyzed Methods for Aerobic Oxidative Lactonization of Diols
Xie, Xiaomin,Stahl, Shannon S.
supporting information, p. 3767 - 3770 (2015/04/14)
Cu/nitroxyl catalysts have been identified that promote highly efficient and selective aerobic oxidative lactonization of diols under mild reaction conditions using ambient air as the oxidant. The chemo- and regioselectivity of the reaction may be tuned by changing the identity of the nitroxyl cocatalyst. A Cu/ABNO catalyst system (ABNO = 9-azabicyclo[3.3.1]nonan-N-oxyl) shows excellent reactivity with symmetrical diols and hindered unsymmetrical diols, whereas a Cu/TEMPO catalyst system (TEMPO = 2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl) displays excellent chemo- and regioselectivity for the oxidation of less hindered unsymmetrical diols. These catalyst systems are compatible with all classes of alcohols (benzylic, allylic, aliphatic), mediate efficient lactonization of 1,4-, 1,5-, and some 1,6-diols, and tolerate diverse functional groups, including alkenes, heterocycles, and other heteroatom-containing groups.
