This usually involves borohydride mediated reduction of the acid moiety, followed by condensation / cyclisation of the resulting amino alcohol with a simple carbonate ester such as diethylcarbonate.
12.
In the above scheme, the reductive cyclisation is effected by Raney nickel and hydrazine . sodium hydrosulfite, or iron in acetic acid are also effective reducing agents.
13.
The cyclohexane and cyclopentane rings, formed by internal cyclisation of one of the biphytane chains, have a pronounced effect on the thermal transition points of the Thaumarchaeotal cell membrane.
14.
As reported in Nature Chemistry, scientists from IBM Research and CiQUS at the University of Santiago de Compostela, demonstrated a reversible Bergman cyclisation for the first time using an atomic force microscope.
15.
They also specify the initial regiospecific folding and cyclisation pattern of nascent polyketides either through the action of a cyclase ( CYC ) subunit or through the combined action of site-specific ketoreductase and CYC subunits.
16.
These include the application of CGCs as catalysts for hydrogenation of imines, hydroboration of alkenes, carboalumination of alkenes, hydrosilylation of alkenes, hydroamination / cyclisation of alpha, omega-aminoalkenes and dimerisation of terminal alkynes.
17.
This is added to an aqueous methanolic solution of basic hydroxylamine at-35 �C followed 15 min later by a pH 7 aqueous buffer so as to give a final pH between 8.5 and 9 for optimum cyclisation.
18.
The second step, an endo trig cyclisation, is driven to one of the two possible enantiomers ( 99 % ee ) because the imine nitrogen atom forms a hydrogen bond with the carboxylic acid group of proline on the Si face.
19.
The final cyclisation reaction of "'60 "'to "'61 "'was facilitated by the central cobalt ion ( placing the ends in close proximity ) and consisted of another type of sulfur contraction employing basic conditions ( diazabicyclononane / dimethylacetamide ).
20.
Other conserved residues include a hydroxyl-containing residue in loop 3, a glycine residue in the final position of loop 3, a basic and a proline residue in the penultimate position in loop 5 of bracelet and M�bius cyclotides respectively, and an asparagine ( or occasionally aspartic acid ) residue at the putative cyclisation point in loop 6.
