Cyclohexene diamination

The kinetic resolution (KR) of racemic mixtures of terminal epoxide catalyzed by chiral metal Salen complexes, such as Cr(Salen) and Co(Salen) (Salen = N,N-bis(3,5-di-tert-butyl-salicylidene)-l,2-cyclohexene diamine), is of great interest in many total syntheses of natural products and drugs. Both Co(Salen) and Cr(Salen)... 

A number of workers have made progress on this front. Asami and coworkers have anchored the stoichiometric base on the solid phase to realize a catalytic desymmetrization using lithiated diamine 135. Andersson has shown that slow addition of LDA results in an improvement in enantioselectivity when using his bicyclic base 136, while Ahlberg has illustrated that a stoichiometric base such as lithiated 1,2-dimethylimidazole results in an efficient catalytic system using diamine 137. Alexakis has published a smdy involving a number of chiral ethane-and propane-diamines in the catalytic deprotonation of cyclohexene oxide. Enan-tioselectivities observed are moderate, with diamine 138 providing the desired product in 59% ee and 80% yield. ... 

The ability of diamine (R,R)-29 to organize the secondary structures of suprami-nols is further confirmed by its recognition properties with diols having functional diversity, as for example (i ,i )-4-cyclohexene-1,2-diol (35) and (R,R,R,R)-4, 5-dibromocyclohexane-1,2-diol (37) [59]. Thus heating equimolar amounts of 29 with 35 and of 29 with 36 in benzene gives the corresponding crystalline complexes suitable for the X-ray analyses (Scheme 15) [60],... 

Thermodynamic studies favour the heterochiral complex over the homochiral complex [56]. On the other hand, crystallization from a mixture seems to favour the matched pairs. Thus, when the mismatched complex 29 48 between (R,R)-trans-1,2-diaminocyclohexane and (S, S)-1,4-cyclohexene- 1,2-diol was heated (melted) with 1 equiv. of the matched (f ,f )-diol, only crystals of the matched pair 29 35 were formed upon cooling (Scheme 21). In a similar way, when the mismatched complex (R,R/S,S)-29 49 was melted with 1 equiv. of the matched diol (f ,f )-32 and the mixture was crystallized from benzene, only crystals of the matched pair (R,RJR,R)-29 32 were obtained (Scheme 21). The corollary that matched diols and diamines compete better in the crystallization and assembly... 

The search for new chiral bases yielding even higher enantioselectivities has resulted in a number of more complex diamines as amide precursors. For example, Asami and coworkers designed the chiral base 14, which in the rearrangement of cyclohexene oxide 1 gave (,S )-cyclohexen-2-ol ((S)-2) in 89% ee (Scheme 10)2°. This result was a significant... 

Thus, the determined composition of lithium amide 4 in the initial state in presence of excess of the corresponding diamine has been used in the kinetics to determine the composition of the activated complexes in cyclohexene oxide deprotonation. It appears... 

There is one direct method of preparing primary diamines from alkoies, in which the alkene is treated with nitric oxide and a cobalt complex, and the intermediate worked up reductively. The two-stage reduction gives better stereoselectivity (Scheme 38). Typical yields from alkenes listed and cisurans se-lectivities (expected product first) are cyclopentene, 70%, 70 30 rr[Pg.484]

Although a mixture of diastereomers was produced from ( )-4-octene, cyclohexene and cyclo-octene afforded the tram-diazides 1 with moderate stereoselectivity. Lindlar s catalyst was recommended for the reduction of diazides to diamines. 

Deoxygenation can be achieved with transition-metal atoms (Ti, V, Cr, Co, Ni) in a high vacuum at low temperature, V and Cr being the most active cis-trans mixtures are obtained with low conversions. The reaction of cyclohexene oxide with transition-metal complexes has been studied on a zeolite matrix of the complexes examined, the copper-phthalocyanine and cobalt-diamine complexes are the most active. 

C. Anaya de Parrodi, E. Juaristi, Chiral 1,2-amino alcohols and 1,2-diamines derived from cyclohexene oxide Recent applications in asymmetric synthesis, Synlett (2006) 2699. 

Polyaminodiols were also prepared by reacting terminal diamines with epoxides. For example, cyclohexene oxide was heated with ethylenediamine or diethylenetriamine to form oligoazadiols containing two 2-hydroxycyclo-hexyl units (Maeda et ah, 1983b). All of these diols internally ring closed to... 

Thus, the determined composition of lithium amide 4 in the initial state in presence of excess of the corresponding diamine has been used in combination with kinetics to determine the composition of the activated complexes in cyclohexene oxide deprotonation. It appears that an activated complex is built from one lithium amide monomer and one epoxide molecule [18]. These results suggest that we are dealing with the TS structures (5)-TS and (R)-TS shown in Scheme 7 leading to the (5)- and (/ )-enantiomer of the allylic alcohol 3, respectively. 

Alexakis et al. the used the combination of the diamine sparteine 1 (Scheme 4) with the Lewis acid BF3-OEt2 for phenyllithium additions to cyclohexene epoxide [Eq. (6)] [105]. They observed that addition of... 

Chiral cyclohexene oxide-derived 1,2-amino alcohols and 1,2-diamines in asymmetric synthesis 06SL2699. 

Later, Berkessel et al. developed a new and improved bis(thio)urea catalysts 365, which was derived in one step from readily available isophorone-diamine (IPDA). Good yields and excellent enantiomeric excesses were obtained in the MBH reaction of cyclohexanecarbaldehyde with 2-cyclohexen-l-one by using bis-thiourea catalyst 365, in combination with a novel base (A,A,A, A -tetra-methylisophorone-diamine, TMIPDA) in toluene (Scheme 2.197). However, with the exception of cyclohexanecarbaldehyde as substrate, DABCO provides superior yields and ee values than TMIPDA. Furthermore, it was shown for the first time that bis-(thio)ureas can activate Michael-acceptors besides 2-cyclohexen-l-one. " °... 

---