Hypervalent λ<sup>3</sup>-Bromane Strategy for Baeyer−Villiger Oxidation: Selective Transformation of Primary Aliphatic and Aromatic Aldehydes to Formates, Which is Missing in the Classical Baeyer−Villiger Oxidation
undergoes BV rearrangement and produces an ester via facile reductive elimination of an aryl-lambda(3)-bromanyl group, because of the hypernucleofugality. The novel strategy makes it possible to induce selectively the BV rearrangement of straight chain primary aliphatic as well as aromatic aldehydes, which is missing in the classical BVO: for instance, octanal and benzaldehyde afforded rearranged formate
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
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