Substrate Structural Effects in Yttrium(III)-Catalyzed Hydroamination/Cyclizations of 1,2-Disubstituted and 1,1,2-Trisubstituted Aminoalkenes Terminated by 2-(Phenyl) and 2-(2-Heteroarenyl) Groups
摘要:
A series of 2-phenyl- and 2-(2-heteroarenyl)-bearing amines possessing 1,2-disubstituted and 1,1,2-trisubststuted alkenes have been evaluated in intramolecular hydroaminations catalyzed by Y[N(TMS)(2)](3) (1(Y)). Aminoalkenes possessing a terminal 2-(5-trimethylsilyl)thienyl group exhibited substantially enhanced reactivity compared to their 2-(phenyl)-containing counterparts. Cyclization efficiencies imparted by the 2-[(5-trimethylsilyl) furanyl] substituent were comparable or only slightly better than those obtained with the simple the 2-(phenyl) group.
Divergent Regioselectivity in the Synthesis of Trisubstituted Allylic Alcohols by Nickel- and Ruthenium-Catalyzed Alkyne Hydrohydroxymethylation with Formaldehyde
作者:Cory C. Bausch、Ryan L. Patman、Bernhard Breit、Michael J. Krische
DOI:10.1002/anie.201101496
日期:2011.6.14
Stoichiometric metals banned: Nonsymmetrically disubstituted alkynes were converted into primary trisubstitutedallylicalcohols upon exposure to paraformaldehyde in the presence of nickel or ruthenium catalysts, which exhibit complementary regioselectivity and complete stereoselectivity in the absence of exogenous reducing agents (see scheme).
Copper-Catalyzed Stereospecific Hydroboration of Internal Allylic Alcohols
作者:Enhui Ji、Haiwen Meng、Yue Zheng、Velayudham Ramadoss、Yahui Wang
DOI:10.1002/ejoc.201901435
日期:2019.11.30
Copper‐catalyzed highly stereospecific hydroboration of internal allylic alcohols using a silyl ether transient protection strategy is reported. This in situ protection effectively avoids the preferential side reaction of free hydroxyl group with boron reagent, thus promoting hydroboration. This method provides both the anti‐ and the syn‐ diastereomers of 1,3‐diols in high level of diastereomeric ratios
Bakers' yeast reduction of thiophenepropaenals. Enantioselective synthesis of (S)-2-methyl-1-alkanols via bakers' yeast mediated reduction of 2-methyl-3-(2-thiophene)propenals
作者:Hans Erik Hoegberg、Erik Hedenstroem、Jonas Faegerhag、Stefano Servi