Trapping of Payne rearrangement intermediates with arylselenide anions
作者:Michael E. Jung、Daniel L. Sun
DOI:10.1016/j.tetlet.2014.11.103
日期:2015.6
The intermediate epoxy alcohols prepared via a Payne rearrangement can be trapped with arylselenide anions, giving mixtures of ring-opened products. The 1-arylseleno-2,3-diols are generally favored over the 3-arylseleno-1,2-diols in this process although the reaction of trisubstituted epoxyalcohols, for example, 17, differs from those of disubstituted epoxyalcohols, for example, 21.
Process for the preparation of substituted pyrrolidine neuraminidase inhibitors
申请人:——
公开号:US20030055297A1
公开(公告)日:2003-03-20
A process for the preparation of neuraminidase inhibitors having structural formula (28)
1
or therapeutically acceptable salts thereof, in which R
1
is alkyl, cycloalkyl, cycloalkylalkyl, or arylalkyl; R
2
is alkyl, cycloalkyl, cycloalkylalkyl, or arylalkyl; R
4
is alkyl, cycloalkyalkyl, or aryl-(C
2
-C
4
-alkyl); R
10
is methyl, ethyl, iso-propyl, or vinyl; and
R
12
is hydrogen or alkyl and intermediates useful for the process are disclosed.
Synthesis of (1S,2R,5R)-2-Ethyl-1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane, the Aggregation Pheromone of Male Beech Bark Beetles,Taphrorychus bicolor (Col., Scol.)
作者:Wittko Francke、Frank Schröder、Ulrich Kohnle、Matthias Simon
DOI:10.1002/jlac.199619961005
日期:1996.10
acetal 2-ethyl-1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane (1), identified as an aggregationpheromone of males of the beechbarkbeetle, Taphrorychusbicolor, was determined by unambiguous synthesis and NMR experiments. The syntheses of the racemates of both diastereomers and of optically pure samples are described. The natural product proved to show (1S,2R,5R) configuration.
A One-Pot Non-Aldol-Aldol Vinylogous Mukaiyama Aldol Tandem Sequence for the Rapid Construction of Polyketide Frameworks
作者:Markus Kalesse、Nicola Rahn
DOI:10.1055/s-2005-863743
日期:——
The rapid assembly of polyketide segments remains one central task in the field of natural product synthesis. Besides the stereoselective assembly of carbon frameworks functional group transformations and protecting group manipulations have to be optimized in order to streamline organic synthesis. The activated aldehyde derived from Jung’s non aldol-aldol method serves as an intermediate for the subsequent vinylogous Mukaiyama aldol reaction.
New opticallyactive hydroxamic acids bearing a 1,1′-binaphthyl group were prepared as ligands in a vanadium-catalyzed asymmetricepoxidation. The feature of these hydroxamic acids is a sterically hindered ligand. The asymmetricepoxidation with good selectivity and reactivity can be established by using VO(O-i-Pr)3 (5 mol%) and a small excess amount of ligand (7.5 mol%) with triphenylmethyl hydroperoxide
在钒催化的不对称环氧化反应中,制备了带有 1,1'-联萘基团的新型旋光异羟肟酸作为配体。这些异羟肟酸的特征是空间位阻配体。在-20 °C 的甲苯中,使用 VO(Oi-Pr)3 (5 mol%) 和少量过量的配体 (7.5 mol%) 与三苯甲基氢过氧化物 (TrOOH) 可以建立具有良好选择性和反应性的不对称环氧化反应. 二取代的烯丙醇比单取代或三取代的烯丙醇环氧化得更快,并且以良好到高的对映选择性 (48-94%ee) 获得。讨论了基于 1e 的 X 射线晶体结构的过渡态。