Hunig base

Amino-anilino)-l, 2-diphenyl-cyclopropenylium-tetrafluoroborat [mesomer mit (2-Amino-phenyl)-(l,2-diphenyl-cyclopropenyliden)-ammonium-tetrafluoroborat] cyclisiert beim Ver-such der Deprotonierung mit molaren Mengen an Diisopropyl-ethyl-amin (Hunig-Base) unter Ringspaltung zu 2-[(Z)-l,2-Diphenyl-ethenyl -benzimidazol (89% Schmp. 273-2740)59 (vgl. 

Hunig base W,W-dimethyl-l -naphthalenamine polymeric Hunig base diisopropyl- Raney Ni Ni-Al alloy treated with aq. NaOH (reductant, hydrogenation catalyst)... 

Similarly, an intramolecular variant utilizing carbamates 26 derived from allylic alcohols has been developed using an amine like Hunigs base (ethyl diisopropylamine) as additive [21], The products were obtained with complete regio- and diastereocontrol, but surprisingly, only in racemic form when chiral ligands like (DHQ PHAL, being established for the AA, were employed. 

Since the original paper, milder bases have been used, including triethylamine and disopropylethylamine (Hunigs base). Again, there is strong preference for the formation of the ( )-alkene when the coupling partner is an aldehyde. 

See also Phosphonic acids, alkyl-, diesters) Hunig base. See 1-Naphthalenamine, M V dimethyl-... 

Hunig bases, polymeric = animated cbloro-methylated ethenylbenzene homopolymers deprotonation with of ketones, 11 or phosphonium salts, 32 removal of acids with, 32 Hybrid plasmids, 243-245 Hydration. See Alkenes or Alkynes Hydrazine hydrazinolysis with of esters, 239-240,331 of phthaloyl-protected amines, 162,163 reduction of ketones with, 97-98,109 Hydrazines, cyclic oxn., N3 extrusion, 35,331 Hydrazones WolfF-Kishner redn. of, 109 —, aryl- indole synth. with, 151-152, 296, 307 —, dialkyl-, lithiated alkylation, 12, 18, 25-26 enantioselective (SAMP-hydrozones), 25-26 ozonolysis of, 26... 

The first one consisted of a four-step reaction sequence [35] formation of the Schiff base (84) by condensation of the 7a-amino derivative (83) with chloral 1,4-dehydrochlorination with Hunig base affording the imine (85) borohydride reduction giving (86) and subsequent acid hydrolysis to 7p-amino-l-oxacephem (87). In this epimerization, the three-step conversion from (84) to (87) was performed as a one-pot reaction in an overall yield of 93%. Also, it should be emphasized that the alkali metal borohydride reduction of (85) proceeded in a highly stereoselective manner, with no trace of the 7a-amino isomer in the products. In contrast, the unsubstituted imino analog (88), prepared in situ by either A-chlorination of (83) or treatment of 7p-amino-7a-methoxy-l-oxacephem (41) with methanolic hydrogen chloride gave a 1 1 mixture of 7a-... 

Elimination Reactions. A Cu(OTf)2/Hunig base combination provides a useful method for converting l,l-bis(phenylthio)-cyclobutanes to l-(phenylthio)cyclobutenes (eq 12) ... 

Acid chlorides reacted with aromatic aldehydes in the presence of a stoichiometric amount of Hunig base and catalytic amounts of a cinchona alkaloid derivative (TMSDQ) and a Lewis acid to produce p-lactones in high diastereo- and enantioselectivities [141]. Sc(OTf)3 was found to be the most effective Lewis acid in the formation of -lactones with alkyl substituents at the a-position (Scheme 12.55). The diastereo- and enantioselectivities were relatively unaffected by changing the electronic nature of the aldehydes. 

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