Synthesis of Glucosides Related to Grape and Wine Aroma Precursors
摘要:
Syntheses of the following glucosides are reported: 3',5',5'-trimethyl-3'-cyclohexenyl beta-D-glucopyranoside, 3'-(1 ''-cyclohexenyl)-1'-methyl-2'-propynyl-beta-D-glucopyranoside, (3'R*,9'S*)-3'-hydroxy-5'-megastigmen-7'-yn-9'-yl beta-D-glucopyranoside, (E,3'R*)-7'-oxo-5',8'-megastigmadien-3'-yl beta-D-glucopyranoside, and 4'-oxo-5'-megastigmen-9'-yl beta-D-glucopyranoside.
with a lipase produced the regio- and enantioconvergent transformation of racemic allyl alcohols (1 or 2) into optically active allyl esters. In this system, the vanadium compounds catalyzed the continuous racemization of the alcohols along with the transposition of the hydroxyl group, while the lipase effected the chemo- and enantioselective esterification to achieve the dynamickineticresolution.
Synthesis of substituted quinolines by the electrophilic cyclization of n-(2-alkynyl)anilines
作者:Xiaoxia Zhang、Tuanli Yao、Marino A. Campo、Richard C. Larock
DOI:10.1016/j.tet.2009.12.012
日期:2010.2
A wide variety of substituted quinolines are readily synthesized under mild reaction conditions by the 6-endo-dig electrophilic cyclization of N-(2-alkynyl)anilines by ICl, I2, Br2, PhSeBr, and p-O2NC6H4SCl. The reaction affords 3-halogen-, selenium- and sulfur-containing quinolines in moderate to good yields in the presence of various functional groups. Analogous quinolines bearing a hydrogen in the
Polymethylhydrosiloxane (PMHS) as an Additive in Sonogashira Reactions
作者:Robert E. Maleczka Jr.、William P. Gallagher
DOI:10.1055/s-2003-37522
日期:——
Polymethylhydrosiloxane (PMHS) in combination with CsF facilitates the Sonogashira reaction of a variety of alkynes and electrophiles. These couplings appear to involve the in situ formation and reaction of an alkynylsiloxane. Such couplings can be run amine free at room temperature, reaction times are short, workup is easy, and product purification is straightforward. Thus, the advantages (and disadvantages) of running Sonogashira couplings with 1-silylalkynes are realized, without the need to preform the alkynyl silane.
PMHS-Mediated Couplings of Alkynes or Benzothiazoles with Various Electrophiles: Application to the Synthesis of (−)-Akolactone A
作者:William P. Gallagher、Robert E. Maleczka
DOI:10.1021/jo034463+
日期:2003.8.1
Polymethylhydrosiloxane (PMHS) in combination with CsF facilitates the cross-coupling of alkynes or benzothiazoles with an array of vinyl, styryl, and aryl halides or nonaflates as well as acid chlorides. Experimental and spectroscopic evidence indicates that these reactions involve the in situ generation of a siloxyl intermediate. These cross-couplings proceed relatively quickly at room temperature
Lipase-catalyzed asymmetric synthesis of naphtho[2,3-c]furan-1(3H)-one derivatives by a one-pot dynamic kinetic resolution/intramolecular Diels–Alder reaction: Total synthesis of (−)-himbacine
(Z)-3-(phenylsulfonyl)acrylate underwent an intramolecular Diels–Alder reaction in a one-pot procedure to produce an optically active naphtho[2,3-c]furan-1(3H)-one derivative (98% ee). This method was successfully applied to the asymmetrictotalsynthesis of (−)-himbacine.
很少研究使用通过醇的酶动力学动力学拆分而安装的酰基部分的一锅顺序反应。在这项工作中,通过脂肪酶/氧钒组合催化的外消旋二烯醇[4-(cyclohex-1-en-1-yl)but-3-en-2-ol或1-( (Z)-3-(苯磺酰基)丙烯酸酯与环己基1-en-1-基)丁-2-烯-1-醇]通过一锅法进行分子内Diels-Alder反应以产生光学活性萘并[2,3 - c ]呋喃-1(3 H)-一衍生物(98%ee)。该方法已成功应用于(-)-半胱氨酸的不对称全合成。