90192-48-6Relevant academic research and scientific papers
12-Substituted-13,14-dihydroretinols designed for affinity labeling of retinol binding- and processing proteins
Yefidoff, Revital,Albeck, Amnon
, p. 8093 - 8102 (2004)
All-trans- and 11-cis-retinol derivatives substituted with various electron-withdrawing groups at C12 were designed to be affinity labels for retinol binding and processing proteins. Unlike other non-selective highly reactive affinity labels, these compounds carry a Michael acceptor type substitution at C12 of the polyene chain. Therefore, they are expected to be highly selective towards such proteins that have a nucleophilic residue near the C11 position of their retinol ligand. The synthetic route for these compounds is based on the Emmons-Horner reaction of a C15 aldehyde with an appropriate phosphonate bearing the desired electron-withdrawing group to be incorporated at the C12 position of the retinol skeleton. Graphical abstract
Hydroboration. 57. Hydroboration with 9-Borabicyclononane of Alkenes Containing Representative Functional Groups
Brown, Herbert C.,Chen, Jackson C.
, p. 3978 - 3988 (2007/10/02)
The hydroboration of alkenes containing representative functional groups was examined with 9-borabicyclononane (9-BBN) in order to extend the hydroboration reaction for the preparation of functionally substituted organoboranes.Terminal alkenes containing a remote functional group are hydroborated with a remarkable regioselectivity (>=98percent terminal), producing the corresponding stable organoboranes. 9-BBN hydroborates the allylic derivatives so as to place boron essentially on the terminal carbon atom (>=97percent).The directive effect is further enhanced (>=99percent) in the case of β-methylallyl derivatives.The hydroboration of crotyl derivatives attaches boron predominantly at the 2-position, followed by an elimination-rehydroboration sequence.However, crotyl alcohol can be protected against elimination as the tert-butyl or tetrahydropyranyl ethers.The hydroboration-oxidation of ethyl crotonate involves a series of elimination, hydroboration, and condensation processes.In the vinyl, crotyl, and isobutenyl systems, the mesomeric effect of the substituent favors the placement of boron at the β-position, while the inductive effect favors the α-position, with the former effect predominating in most cases.Acyclic β-substituted organoboranes undergo rapid elimination.Nonpolar solvents and lower reaction temperatures decrease the rate of elimination.However, those derived from cyclic vinyl derivatives are relatively stable under neutral conditions, undergoing facile elimination in the presence of a base.
