Synthesis of the (5S,9R)-isomer of 5,9-dimethylpentadecane, the major component of the female sex pheromone of the coffee leaf miner moth, Leucoptera coffeella
Highly Enantioselective α Alkylation of Aldehydes with 1,3-Benzodithiolylium Tetrafluoroborate: A Formal Organocatalytic α Alkylation of Aldehydes by the Carbenium Ion
作者:Andrea Gualandi、Enrico Emer、Montse Guiteras Capdevila、Pier Giorgio Cozzi
DOI:10.1002/anie.201102562
日期:2011.8.16
A formal formyl: The organocatalytic stereoselective addition of formyl equivalents to aldehydes (see scheme) tolerates a large variety of functional groups to afford products with high enantioselectivity (92–97 % ee) and good yields (up to 95 %). The benzodithiol group can be easily removed with Raney Ni or metalated with nBuLi, thus giving access to a methyl group or to a wide range of useful intermediates
Synthesis of All the Stereoisomers of 7-Methylheptadecane and 7,11-Dimethylheptadecane, the Female Sex Pheromone Components of the Spring Hemlock Looper and the Pitch Pine Looper
the stereoisomers of 7-methylheptadecane (1) and 7,11-dimethylheptadecane (2) were synthesized by starting from the enantiomers of citronellol (3) and methyl 3-hydroxy-2-methylpropanonate (8), respectively. A short synthesis of meso-7,11-dimethylheptadecane [(7R,11S)-2] was achieved starting from meso-2,6-dimethylheptanedioic acid [(2R,6S)-21]. A mixture of (S)-1 and (7R,11S)-2 is the pheromone of the
Manganese-Catalyzed Stereospecific Hydroxymethylation of Alkyl Tosylates
作者:Hannah Shenouda、Erik J. Alexanian
DOI:10.1021/acs.orglett.9b03706
日期:2019.11.15
The development of a stereospecific hydroxymethylation of alkyl tosylates using an inexpensive, first-row catalyst is described. The transformation proceeds under mild conditions with low pressure to deliver homologated alcohols as products. Chiral, nonracemic β-branched primary alcohols are obtained with high enantiospecificity from easily accessed secondary alkyl substrates. Simple modification of
ZACA–lipase-catalyzed acetylation tandem reactions provide highly efficient and selective routes to either (R)- or (S)-2-methyl-1-alkanols, making, for the first time, the ZACA-based asymmetric synthesis of 2-methyl-1-alkanols widely applicable and satisfactory.
photoexcitation of enamines to trigger the formation of reactive carbon-centered radicals from iodosulfones, while the ground-state chiral enamines provide effective stereochemicalcontrol over the radical trapping process. The phenylsulfonyl moiety, acting as a redox auxiliary group, facilitates the generation of radicals. In addition, it can eventually be removed under mild reducing conditions to reveal methyl