Binaphthyl guanidines

Thereafter, Terada applied related binaphthyl guanidine base catalyst 24 to the asymmetric 1,4 addition of diphenylphosphite to nitroalkenes (Scheme 5.45) [81]. 

GABA HMG-CoA HMPA HT LDA LHMDS LTMP NADH NBH NBS NCS NIS NK NMP PMB PPA RaNi Red-Al RNA SEM SnAt TBAF TBDMS TBS Tf TFA TFP THF TIPS TMEDA TMG TMP TMS Tol-BINAP TTF y-aminobutyric acid hydroxymethylglutaryl coenzyme A hexamethylphosphoric triamide hydroxytryptamine (serotonin) lithium diisopropylamide lithium hexamethyldisilazane lithium 2,2,6,6-tetramethylpiperidine reduced nicotinamide adenine dinucleotide l,3-dibromo-5,5-dimethylhydantoin A-bromosuccinimide A-chlorosuccinimide A-iodosuccinimide neurokinin 1 -methyl-2-pyrrolidinone para-methoxybenzyl polyphosphoric acid Raney Nickel sodium bis(2-methoxyethoxy)aluminum hydride ribonucleic acid 2-(trimethylsilyl)ethoxymethyl nucleophilic substitution on an aromatic ring tetrabutylammonium fluoride tert-butyldimcthyisilyl fert-butyldimethylsilyl trifluoromethanesulfonyl (triflyl) trifluoroacetic acid tri-o-furylphosphine tetrahydrofuran triisopropylsilyl A, N,N ,N -tetramethy lethylenediamine tetramethyl guanidine tetramethylpiperidine trimethylsilyl 2,2 -bis(di-p-tolylphosphino)-l,r-binaphthyl tetrathiafulvalene... 

An axially chiral and highly hindered binaphthyl-derived guanidine catalyst 18a with an internal guanidine unit (Figure 4.6) facilitates the highly enantioselective 1,4-addition... 

To overcome the difficulty associated with the design of chiral guanidines as a catalyst, the binaphthyl-derived 22 was initially developed with the expectation that substituents at the 3,3 -positions of the binaphthyl backbone would break the planar symmetry of the guanidine skeleton to create an attractive chiral environment. This type of axially chiral organic base catalyst, particularly 22a, could indeed... 

On the other hand, 22a bearing sterically demanding aromatic substituents on the binaphthyl unit and the small methyl group on the guanidine nitrogen turned out to be a catalyst of choice for the [4-e2] cycloaddition of azlactone to P.y-unsaturated a-ketoesters, which proceeded through three consecutive transformations to afford a-amino-8-lactone derivatives with high diastereo- and enanti-oselectivities (Scheme 7.40) [64]. 

---