BCl3- and TiCl4-Mediated Reductions of β-Hydroxy Ketones
摘要:
Syn-selective reduction protocols for beta-hydroxy ketones are described exploiting the intermediacy of titanium and boron chelates derived from TiCl4 and BCl3, respectively, Reductions are conducted at -78 degrees C in CH2Cl2 using a wide range of CH2Cl2-soluble reducing agents, Added acid-scavenging agents are detrimental to reaction selectivity, An A((1,3))-like interaction involving the stereocenter responsible for asymmetric induction provides conformational biasing of the intermediate chelates necessary for high diastereoselectivity.
A new strategy using a BINOL derivative as a chiral leaving group and Lewis acid has been developed for enantioselective alkylation of prochiral olefins. (R)-2,2'-Bis[2-(trimethylsilyl)ethoxymethyl]-1,1'-binaphthol is demonstrated to be an effective reagent for enantioselective hydroxymethylation of silyl enol ethers and trisubstituted alkenes. Electrophilic addition to prochiral olefins is accompanied
TREPROSTINIL DERIVATIVES AND COMPOSITIONS AND USES THEREOF
申请人:CORSAIR PHARMA, INC.
公开号:US20180016222A1
公开(公告)日:2018-01-18
The present disclosure provides treprostinil derivatives that can act as prodrugs of treprostinil. The treprostinil derivatives can be used to treat any conditions responsive to treatment with treprostinil, including pulmonary hypertension, such as pulmonary arterial hypertension.
US9394227B1
申请人:——
公开号:US9394227B1
公开(公告)日:2016-07-19
[EN] PROCESS FOR THE PREPARATION OF 2,2,4,4-TETRAALKYLCYCLOBUTANE-1,3-DIOLS<br/>[FR] PROCÉDÉ POUR LA PRÉPARATION DE 2,2,4,4-TÉTRAALKYLCYCLOBUTANE-1,3-DIOLS
申请人:EASTMAN CHEM CO
公开号:WO2012078384A1
公开(公告)日:2012-06-14
Disclosed is a process for the preparation of a 2,2,4,4-tetraalkylcyclobutane-1,3-diol by hydrogenation of the corresponding 2,2,4,4-tetraalkylcyclobutane-1,3-dione in the vapor phase in the presence of a supported catalyst. The process is useful for the preparation of 2,2,4,4-tetramethylcyclobutane-1,3-diol from 2,2,4,4-tetramethylcyclobutane-1,3-dione. The process can produce a 2,2,4,4-tetraalkylcyclobutane-1,3-diol product having a cis:trans isomer ratio of 1:1 or greater.