A catalytic allylic cation-induced intermolecular allylation-semipinacol rearrangement

2018 ◽  
Vol 54 (55) ◽  
pp. 7685-7688 ◽  
Author(s):  
Ming-Hui Xu ◽  
Kun-Long Dai ◽  
Yong-Qiang Tu ◽  
Xiao-Ming Zhang ◽  
Fu-Min Zhang ◽  
...  
Keyword(s):  
Allylic Cation ◽  
Semipinacol Rearrangement

A catalytic intermolecular semipinacol rearrangement induced by allylic carbocations has been realized and used in the synthesis of α-homoallyl ketones.

scholarly journals Recent development and applications of semipinacol rearrangement reactions

2021 ◽  
Author(s):  
Xiao-Ming Zhang ◽  
Bao-Sheng Li ◽  
Shao-Hua Wang ◽  
Kun Zhang ◽  
Fu-Min Zhang ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Quaternary Carbon ◽  
Carbon Formation ◽  
Semipinacol Rearrangement ◽  
Rearrangement Reactions

The recent development of semipinacol rearrangement is reviewed, highlighting its application in β-functionalized ketone synthesis, quaternary carbon formation and total synthesis.

The tamoxifen cation reacts to give indene products

2000 ◽  
Vol 78 (9) ◽  
pp. 1186-1193
Author(s):  
Cristina Sanchez ◽  
Robert A McClelland
Keyword(s):  
Intramolecular Cyclization ◽  
Phenyl Ring ◽  
Irreversible Process ◽  
Total Yield ◽  
Cellular Systems ◽  
Acid Solutions ◽  
Allylic Cation ◽  
Super Acid ◽  
Acidic Conditions

The tamoxifen carbocation (Ph(Ar)C=CPh-CH+-CH3, Ar = 4-Me2NCH2CH2OC6H4) is generated from acetate and sulfate precursors by SN1 ionization in water. The cation exists in (E) and (Z) forms which equilibrate before reaction. The major products are the α-hydroxytamoxifens Ph(Ar)C=CPh-CHOH-CH3, both (E) 64% and (Z) 29%, with the ratio independent of the configuration of the starting ester. Two minor products with a total yield of 7% account for the rest of the products. These have been characterized as indenes derived from intramolecular cyclization, a 4.5% yield of the indene derived from cyclization into the Ar ring with 2.5% due to cyclization into the phenyl ring. Experiments in acid solutions (0.01-0.1 M HCl) starting with pure (E)- or (Z)-α-hydroxytamoxifen reveal that the two alcohols equilibrate. This occurs by H+-catalyzed formation of the carbocation followed by water capture. Occurring about 10-fold slower than this isomerization is an irreversible process resulting in the two indenes. This cyclization will result in the destruction of the α-hydroxytamoxifens upon exposure to acidic conditions and also makes the direct observation of the tamoxifen carbocation under super-acid conditions difficult, if not impossible. The indenes do form in low yield whenever the tamoxifen carbocation is generated from an SN1 precursor. Thus these products could serve as markers for the formation of the tamoxifen carbocation in cellular systems or in in vivo experiments.Key words: carbocation, indene, allylic cation, isomerization.

Total synthesis of (±)-Lingzhilactone B via semipinacol rearrangement

2016 ◽  
Vol 57 (26) ◽  
pp. 2877-2879 ◽  
Author(s):  
Dong Chen ◽  
Xiao-Mei Li ◽  
Hao-Miao Liu ◽  
Ming-Ming Li ◽  
Yong-Xian Cheng ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Semipinacol Rearrangement

Semipinacol Rearrangement

2007 ◽  
pp. 1
Author(s):  
M. Kalesse
Keyword(s):  
Semipinacol Rearrangement

Synthesis of the C1–C17 Segment of Bafilomycin N

Synlett ◽  
2019 ◽  
Vol 30 (05) ◽  
pp. 577-580 ◽  
Author(s):  
Seijiro Hosokawa ◽  
Haruka Sato
Keyword(s):  
Aldol Reaction ◽  
Stille Coupling ◽  
Mukaiyama Aldol Reaction ◽  
Mukaiyama Aldol ◽  
Semipinacol Rearrangement

The C1–C17 segment of bafilomycin N has been synthesized. The C1–C11 segment was synthesized by the anti-selective vinylogous Mukaiyama aldol reaction with a chiral vinylketene silyl N,O-acetal and the Horner–Wadsworth–Emmons reaction, whereas C12–C17 was constructed by the syn-selective vinylogous Mukaiyama aldol reaction and the Jung’s semipinacol rearrangement. Those segments were connected by the Stille coupling to afford the C1–C17 segment.

Lewis base mediated halogenation/semipinacol rearrangement of diazo compounds: new access to α-halo-quaternary ketones

2014 ◽  
Vol 50 (68) ◽  
pp. 9773-9775 ◽  
Author(s):  
Haibin Mao ◽  
Zhongkai Tang ◽  
Hongwen Hu ◽  
Yixiang Cheng ◽  
Wen-Hua Zheng ◽  
...  
Keyword(s):  
Lewis Base ◽  
Diazo Compounds ◽  
Semipinacol Rearrangement

A novel halogenation/semipinacol rearrangement of α-diazo alcohol catalyzed by Lewis base has been developed through a carbene-free mechanism.

Synthesis of 2-(2-Oxo-2-phenylethyl)cyclopentanone by Rhodium-Catalyzed Tandem Alkynyl Cyclobutanols Hydroacylation and Semipinacol Rearrangement

2019 ◽  
Vol 21 (5) ◽  
pp. 1263-1267 ◽  
Author(s):  
Rui Guo ◽  
Xueling Mo ◽  
Guozhu Zhang
Keyword(s):  
Semipinacol Rearrangement
Sign in / Sign up

Export Citation Format

Share Document