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Allenes are important building blocks in organic synthesis and have attracted much attention from researchers worldwide. So far, mono-and 1,3-disubstituted allenes can be prepared easily by applying the allenylation of terminal alkynes reaction of aldehydes. However, trisubstituted allenes have never been reported using this reaction due to the extremely low reactivity of ketones. Here, we report the one-pot synthesis of trisubstituted allenes from terminal alkynes and ketones utilizing cadmium iodide as the mediator. With this protocol, a series of different allenes, including 1,5-bisallenes and optically active allenols, which are especially important in synthetic chemistry, have been successfully prepared.

Tetrahydroisoquinoline alkaloids with a C1 stereogenic center are a common unit in many natural and non-natural compounds of biological importance. Herein we describe a novel Cu(I) -catalyzed highly chemo- and enantioselective synthesis of chiral tetrahydroisoquinoline-alkaloid derivatives from readily available unsubstituted tetrahydroisoquinolines, aldehydes, and terminal alkynes in the presence of the ligand (R,R)-N-pinap. This synthetic operation installs two substituents in the 1- and 2-positions.

Here, we show a CuBr2-catalyzed approach for a highly enantioselective synthesis (93-99% ee) of allenols from aldehydes and terminal alkynols with the absolute configuration being controlled by applying readily available (R)- or (S)-α,α-diphenylprolinol.

The generation of substituted gamma-lactones can be accomplished through application of a tandem chain extension-aldol reaction, followed by CAN-mediated oxidative cleavage of the aldol product. The oxidative cleavage requires the intermediacy of a hemiketal and the presence of an alpha-heteroatom. Formation of the gamma-lactone through the oxidative cleavage is used to assign stereochemistry of the aldol reaction and as the final step in a short synthesis of members of the phaseolinic acid family of natural products.

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Here we show the CuBr 2 -catalyzed approach for highly enantioselective synthesis (90-98% ee) of allenes bearing a very broad array of unmasked synthetically attractive functionalities from aldehydes and terminal alkynyl bearing reactive functionalities with the absolute configuration controlled by applying readily available (R)-or (S)-α,α-diphenylprolinol. Following this protocol, the highly enantioselective synthesis of some naturally occurring allenes loaded with reactive functionalities becomes simple: a terminal alkyne plus an aldehyde. In comparison, they were reported to be synthesized either from similar level generic chemicals with much more steps or in lower ees.

β 2-and β 3-Amino acids are important chiral building blocks for the design of new pharmaceuticals and peptidomimetics. Here we report a straightforward regio-and enantiodivergent access to these compounds using a one-pot reaction composed of sparteinemediated enantioselective lithiation of a Boc-1,3-oxazinane, transmetallation to zinc and direct or migratory Negishi coupling with an organic electrophile. The regioselectivity of the Negishi coupling was highly ligand-controlled and switchable to obtain the C4-or the C5-functionalized product exclusively. High enantioselectivities were achieved on a broad range of examples, and a catalytic version in chiral diamine was developed using the (+)-sparteine surrogate. Selected C4and C5-functionalized Boc-1,3-oxazinanes were subsequently converted to highly enantioenriched β 2-and β 3-amino acids with the (R) or (S) configuration, depending on the sparteine enantiomer employed in the lithiation step. Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use: