The effects of phosphorus substituents on the reactivity of α‐alkoxyphosphonium salts with nucleophiles has been explored. Reactions of α‐alkoxyphosphonium salts, prepared from various acetals and tris(o‐tolyl)phosphine, with a variety of nucleophiles proceeded efficiently. These processes represent the first examples of high‐yielding nucleophilic substitution reactions of α‐alkoxyphosphonium salts
Rearrangement of Hydroxylated Pinene Derivatives to Fenchone-Type Frameworks: Computational Evidence for Dynamically-Controlled Selectivity
作者:Marcus Blümel、Shota Nagasawa、Katherine Blackford、Stephanie R. Hare、Dean J. Tantillo、Richmond Sarpong
DOI:10.1021/jacs.8b05804
日期:2018.7.25
An acid-catalyzed Prins/semipinacolrearrangementcascade reaction of hydroxylated pinene derivatives that leads to tricyclic fenchone-type scaffolds in very high yields and diastereoselectivity has been developed. Quantum chemical analysis of the selectivity-determining step provides support for the existence of an extremely flat potential energy surface around the transition state structure. This
Catalytic Use of Elemental Gallium for Carbon–Carbon Bond Formation
作者:Bo Qin、Uwe Schneider
DOI:10.1021/jacs.6b06767
日期:2016.10.12
The first catalytic use of Ga(0) in organic synthesis has been developed by using a Ag(I) cocatalyst, crownether ligation, and ultrasonic activation. Ga(I)-catalyzed C-C bondformations between allyl or allenyl boronic esters and acetals, ketals, or aminals have proceeded in high yields with essentially complete regio- and chemoselectivity. NMR spectroscopic analyses have revealed novel transient Ga(I)
A highly efficient metal-free aldol-type reaction of various acetals or ketals with fluorinated silylenolethers catalysed by less than 1 mol% HClO4 (70 wt%, aq.) is developed. This provides expedient access to a wide array of valuable fluoroalkyl ethers featuring a ketone carbonyl functionality in good to excellent yields (40 examples). Furthermore, the thus obtained adducts are readily elaborated
An unusual and novel reaction of alpha-alkoxyphosphonium salts, generated from O,O-acetals and Ph(3)P, with Grignard reagents under an O(2) atmosphere afforded alcohols in moderate to high yields. It was clarified by isotopic labelling experiments that the reaction proceeded via a novel radical pathway.