improved generation of chiral cationic iridium catalysts for the asymmetricisomerization of primaryallylicalcohols is disclosed. The design of these air‐stable complexes relied on the preliminary mechanistic information available, and on Charton analyses using two preceding generations of iridium catalysts developed for this highly challenging transformation. Sterically unbiased chiral aldehydes
Asymmetric Traceless Petasis Borono‐Mannich Reactions of Enals: Reductive Transposition of Allylic Diazenes
作者:Yao Jiang、Regan J. Thomson、Scott E. Schaus
DOI:10.1002/anie.201708784
日期:2017.12.22
The traceless Petasis borono‐Mannich reaction of enals, sulfonylhydrazines, and allylboronates, catalyzed by chiral biphenols, results in an asymmetric reductivetransposition of the in situ generated allylic diazene. Acyclic 1,4‐diene products bearing either alkyl‐ or aryl‐substituted benzylic stereocenters are afforded in excellent yields and enantiomeric ratios of up to 99:1. The use of crotylboronates
作者:Francesco G. Gatti、Fabrizio Antonietti、Elisabetta Brenna、Claudio Fuganti、Tommaso Giovenzana、Valentina Grande、Luciana Malpezzi
DOI:10.1055/s-2005-861856
日期:——
A lipase-mediated synthesis of all four enantiomers of isoaminile is reported. The key issues of the paper are: (i) enantioselective acetylation of allylic alcohol (E)-(′)-5 to give (E,S)-5 (ee = 92%) and (E,R)-6 (ee >99%); (ii) Claisen-Johnson rearrangement of R and S enantiomers of 5 to generate the quaternary benzylic stereocenter; (iii) chromatographic separation of aldehyde diastereoisomers; (iv)
报告了异胺的所有四种对映异构体的脂肪酶介导的合成。该论文的关键问题是:(i)烯丙醇(E)-(')-5的对映选择性乙酰化得到(E,S)-5(ee = 92%)和(E,R)-6(ee >99%);(ii) 5 的 R 和 S 对映异构体的 Claisen-Johnson 重排以产生季苄基立体中心;(iii) 醛类非对映异构体的色谱分离;(iv) 醛 (2R,4R)-10 的 X 射线结构;(v) 在 11 的水解过程中意外形成内酯 12。
Highly Enantioselective Asymmetric Isomerization of Primary Allylic Alcohols with an Iridium-N,P Complex
作者:Jia-Qi Li、Byron Peters、Pher G. Andersson
DOI:10.1002/chem.201101524
日期:2011.9.26
Access to chiral aldehydes: The asymmetricisomerization of primaryallylicalcohols was studied with a bicyclic phosphine‐oxazoline iridium catalyst. This method displays a broad substrate scope and leads to the desired chiral aldehydes with excellent enantioselectivities (see scheme; R1, R2=Ar or alkyl).
接触手性醛:使用双环膦-恶唑啉铱催化剂研究了伯烯丙基醇的不对称异构化。该方法显示出较宽的底物范围,并得到具有优异对映选择性的所需手性醛(参见方案; R 1,R 2= Ar或烷基)。
Unconventional isomerization of allylic alcohols to allylcarbinols mediated by lanthanide catalysts
作者:SungYong Seo、Xianghua Yu、Tobin J. Marks
DOI:10.1016/j.tetlet.2013.01.111
日期:2013.4
We report here the catalytic isomerization of aryl-substituted allylic alcohols mediated by lanthanide alkoxide complexes. The conversion yields allylcarbinols as the products of the olefin isomerization process, but with different olefinic positions than those afforded by typical transition metal catalysts. The average isolated product yields in these reactions are 65–81%. The catalytic cycle and