10281-56-8Relevant articles and documents
Hydroboration. 86. Convenient Conversion of Aldehydes and Ketones into the Corresponding Alkenes via Hydroboration of their Enamines. A Remarkably Simple Synthesis of Either (Z)- or (E)-Alkenes
Singaram, Bakthan,Rangaishenvi, Milind V.,Brown, Herbert C.,Goralski, Christian G.,Hasha, Dennis L.
, p. 1543 - 1549 (1991)
Aldehydes and ketones are converted into the corresponding alkenes via hydroboration of their enamines.Hydroboration of aldehyde enamines by 9-borabicyclononane (9-BBN), followed by methanolysis, affords the corresponding terminal alkenes in 75-90percent yields.Unsaturated aldehyde enamines produce the corresponding dienes under these conditions.Enamines derived from substituted cyclic ketones and heterocyclic ketones are readily accommodated in this reaction to afford the corresponding alkenes in very good yields.The synthesis of pure (Z)- or (E)-alkenes is readily achieved from the same acyclic ketone enamine by modification of the hydroboration-elimination procedure: (A) hydroboration by 9-BBN followed by methanolysis or (B) hydroboration by borane methyl sulfide (BMS) followed by methanolysis and hydrogen peroxide oxidation.Mechanistic rationale is provided.
Arigoni,Jeger
, p. 881 (1954)
(?)-6-epi-artemisinin, a natural stereoisomer of (+)-artemisinin in the opposite enantiomeric series, from the endemic madagascar plant saldinia proboscidea, an atypical source
Randrianarivo, Saholinirina,Rasolohery, Claudine,Rafanomezantsoa, Sitraka,Randriamampionona, Heriniaina,Haramaty, Liti,Rafanomezantsoa, Roger Marie,Andrianasolo, Eric H.
supporting information, (2021/09/20)
Chemical and biological investigation of the Madagascar endemic plant Saldinia proboscidea led to the isolation of an isomer of artemisinin, (?)-6-epi-artemisinin (2). Its structure was elucidated using a combination of NMR and mass spectrometry. The absolute configuration was established by chemical syntheses of compound 2 as well as a new stereoisomer (3). The comparable bioactivities of artemisinin (1) and its isomer (?)-6-epi-artemisinin (2) revealed that this change in configuration was not critical to their biological properties. Bioactivity was assessed using an apoptosis induction assay, a SARS-CoV-2 inhibitor assay, and a haematin polymerization inhibitory activity (HPIA) assay. This is the first report of an artemisinin-related compound from a genus not belonging to Artemisia and it is the first isolation of an artemisinin-related natural product that is the opposite enantiomeric series relative to artemisinin from Artemisia annua.
Tertiary phosphine compound and transition metal complex comprising the same as ligand
-
, (2008/06/13)
A tertiary phosphine compound of the formula (1): STR1 wherein R1 and R2 represent independently from each other a hydrogen atom or a methyl group, or together form --CH=CH--CH=CH--; R3 is a hydrogen atom or a cycloalkyl group having 5 to 7 carbon atoms or a lower alkyl group which may be substituted with a halogen atom, a lower alkoxy group, a lower alkoxyalkoxy group or a phenyl group; X1 is a halogen atom when both R1 and R2 are hydrogen atoms, or a hydrogen atom, a halogen atom, a lower alkyl group or a lower alkoxy group when at least one of R1 and R2 is not a hydrogen atoms; and m is an integer of 1 to 5, which is useful as a ligand of a transition metal complex that can catalyze various reactions.
Practical catalyst for cyclic metathesis. Synthesis of functional and/or enantiopure cycloalkenes
Nugent, William A.,Feldman, Jerald,Calabrese, Joseph C.
, p. 8992 - 8998 (2007/10/02)
The oxo-tungsten complex trans-WOCl2(OAr)2 (Ar = 2,6-dibromophenyl) is prepared by reaction of WOCl4 with 2 equiv of 2,6-dibromophenol. A variety of nonconjugated dienes are cleanly cyclized to the corresponding cycloalkenes using 2 mol % of this catalyst in combination with 4 mol % of tetraethyllead. All three components of the catalyst system are commercially available. The catalytic reactions are typically complete in 1 h at 90 °C and allow the synthesis of chiral cycloalkenes with little or no loss in optical activity. For example, (R)-and (5)-citronellene have been cyclized to the corresponding (R)- or (S)-3-methylcyclopentenes in 97% enantiomeric excess. The cyclization is compatible with a variety of functional groups including some ester, amide, and ether derivatives. Tri- (but not tetra-) substituted cycloalkenes could be prepared using this catalyst.
