Changing stereoselectivity and regioselectivity in copper(<scp>i</scp>)-catalyzed 5-<i>exo</i> cyclization by chelation and rigidity in aminoalkyl radicals: synthesis towards diverse bioactive N-heterocycles
作者:Sandhya Sadanandan、Dharmendra Kumar Gupta
DOI:10.1039/c9nj05166j
日期:——
Chelation, rigidity and carbon-radical positions in aminoalkyl precursors disturb the usual 2,4-trans diastereoselectivity and 5-exo mode in Cu(i)-catalyzed ATRC.
A fundamentally newreagent space has been discovered for the Castagnoli-Cushman reaction. Cyclic anhydride has been successfully replaced with CDI-activated monoesters of homophthalic acid allowing direct preparation of tetrahydroisoquinolonic esters. Mechanistic studies suggested a new reaction pathway not involving any previously described alkoxyisocoumarines.
Rhodium-Catalyzed Regiodivergent Hydrothiolation of Allyl Amines and Imines
作者:Jennifer L. Kennemur、Gregory D. Kortman、Kami L. Hull
DOI:10.1021/jacs.6b07142
日期:2016.9.14
The regiodivergent Rh-catalyzed hydrothiolation of allyl amines and imines is presented. Bidentate phosphine ligands with larger natural bite angles (βn ≥ 99°), for example, DPEphos, dpph, or L1, promote a Markovnikov-selective hydrothiolation in up to 88% yield and >20:1 regioselectivity. Conversely, when smaller bite angle ligands (βn ≤ 86°), for example, dppbz or dppp, are employed, the anti-Markovnikov
Rhodium-catalyzed hydroborations of allylamine and allylimines<sup>1</sup>
作者:Christopher M Vogels、Paul E O'Connor、Trevor E Phillips、Keith J Watson、Michael P Shaver、Paul G Hayes、Stephen A Westcott
DOI:10.1139/v01-177
日期:2001.12.1
afforded only products arising from hydroboration (RN(Bpin)CH2CH2CH2Bpin, where R = H, Bpin) and hydrogenation (RN(Bpin)CH2CH2CH3). Hydroboration of allylimines (RHC=NCH2CH=CH2, R = Ar) with HBcat occurs initially at the more reactive imine functionality to give unsaturated borylamines (RCH2N(Bcat)CH2CH=CH2). Further reaction with HBcat gives varying amounts of hydroboration products RCH2N(Bcat)CH2CH2CH2Bcat
Sequential Metal-Free Thermal 1,3-Dipolar Cycloaddition of Unactivated Azomethine Ylides
作者:Verónica Selva、Elisabet Selva、Pedro Merino、Carmen Nájera、José M. Sansano
DOI:10.1021/acs.orglett.8b01292
日期:2018.6.15
The thermal 1,3-dipolarcycloaddition of unactivated azomethine ylides derived from allylamine and aromatic or heteroaromatic aldehydes with maleimides and 1,1- and 1,2-bis(phenylsulfonyl)ethylene affords endo-2,5-trans cycloadducts in moderate to good yields. DFT calculations provide evidence that the diastereoselectivity observed depends on the isomerization between S- and W-ylides according to Curtin-Hammett’s