Geranylamine

Isoprene (2-methyl-1,3-butadiene) can be telomerized in diethylamine with / -butyUithium as the catalyst to a mixture of A/,N-diethylneryl- and geranylamines. Oxidation of the amines with hydrogen peroxide gives the amine oxides, which, by the Meisenheimer rearrangement and subsequent pyrolysis, produce linalool in an overall yield of about 70% (127—129). 

In order to establish the industrial application, [Rh(BINAP)2]C104 was developed as a new catalyst, which has excellent thermal stability allowing multiple repetition of the catalyst recovery. A further improvement of the catalyst was accomplished by the use of [Rh(TolBINAP)2]Cl04, which possessed a better solubility in organic solvents and achieved even higher optical yields (>98% ee) for the isomerization of allylamines such as geranylamine and nerylamine.15... 

SCHEME 13. NMR spectra of a mixture of BINAP Rh complex and geranylamine. 

Kinetics. Kinetic measurements using [Rh((5)-binap)(CH30H)2]C104 and geranylamine substrate indicate that (1) The initial phase of the reaction obeys the first-order rate law, but as the initial substrate concentration, [substratelo, is increased, the rate starts to deviate from the first-order plots at a relatively early stage of the reaction, implying a product inhibition. (2) The dependence of the initial rate Rq on the initial... 

Like the synthesis of L-DOPA by asymmetric hydrogenation, the manufacture of L-menthol hy Takasago Company is also one of the early examples of an industrial process where asymmetric isomerization is a key step. The desired isomerization reaction is one of the steps of the overall synthetic scheme. The synthesis of L-menthol from diethyl geranylamine is shown by 9.2. The formal electron pair pushing mechanism for the isomerization of the allylic amine to the enamine proceeds according to reaction 9.3. 

The key step of this process is the asymmetric isomerization of (A,A)-diethyl-geranylamine or diethylnerylamine to give (7 )-citronellal ( )-diethylenamine. 

Recently it has become known from work at Firmenich, that BINAP can be effectively replaced by the Josiphos and Daniphos ligands. [129] From diethyl-geranylamine one obtains after hydrolysis (S>citronellal, and from diethyl-nerylamine (R)-citronellal (analogous to (R)-BINAP). By attaching a linker to the unsubstituted cyclopentadiene ring, the catalyst can be immobilised on various carriers. In some cases this reduces the activity, but the stereoselectivity remains comparable. 

C10H20CIN, Geranylamine hydrochloride, 10, 218 Ci H2oN2r N,N -Di-t-butyl-1,2-ethanediimine (gas-ed), 42B, 1024 C,0H2 N2O2, N,N -Diacetylhexamethylenediamine, 19, 513 Cl H24N2O18, Ethylenediamine ditartrate dihydrate, 43B, 43 Ci H28N2Se 0.5 CS2, Tetramethylammonium perthiocarbonate carbon disulfide solvate, 41B, 37... 

---