Morpholine-camphoric acid

Bis(cyclopentadienyl)dichlorozirconium(lI). Chlorotris(isopropoxy)titanium. Di-n-butylboryl trifluoromethanesulfonate. (4S, 5S)-2-Ethyl-4-(methoxymethyl)-5-phenyloxazoline Methyl O-me thy lactate. 2-Methyl-2-trimethylsilyloxypentane-3 one. Morpholine-Camphoric acid. Tin. Tin(II) trifluoromethanesulfonate. 

L-proline followed by reaction of the product with diethyl cyanomethylphosphonate (1, 250 2, 130-131) gives 2 and 3 in a 1 1 ratio (18.3% total yield). Use of piperidine acetate gives 2 and 3 in a 1 22 ratio (50.3% total yield). Dibenzylam-monium trifluoroacetate shows similar selectivity 2/3 = 1 19 (76.4% total yield). However, use of morpholine-camphoric acid in ether-HMPT favors formation of 2. With this catalyst 2 and 3,are obtained in 37.5% and 1.5% yield, respectively. ... 

Molecular sieves, 55, 130, 316-317 Molybdenum carbonyl, 317 Monensin, 136, 137, 173 Monoisopinocampheylboranc, 317 Monothioacetals, 6-7 Monotrimethylsilyl acetamide, 113 Morpholine, 138, 139 Morpholine-Camphoric acid, 317-318 Morpholine enamines, 319 N-Morpholinomethyldiphenylphosphine... 

ALDOL CONDENSATION (+)-(R)-l-Amino-2- methoxymethyl)pyrrolidine. Boron trichloride. Dialkylboron tri-fluoromethanesulfonates. Dibenzyl-ammonium trifluoroacetate. Di- -butylboryl trifluoromethanesulfonate. Dichlorodiethylaminoborane. Diiso-propylaluminum phenoxide. Diisopropyl-aminomagnesium bromide. Lithium diisopropylamide. Morpholine-Camphoric acid. Proline. 

Inubushi and cowoiicers have studied a similar unsymmetrical dialdehyde in the context of their fawcettimine synthesis." Dialdehyde (34) cyclizes under various conditions to give a mixture of enals (35 and 36 equation 100). Unexpectedly, both the Woodward and Corey methods give the same major product, providing (35) (36) ratios of 21 1 (80% yield) and 19 1 (62% yield), respectively. The opposite regioselectivity is obtained by using morpholine and camphoric acid in ether-HMPA solvent under these conditions, the (3S) (36) ratio is 1 25 and the yield is 54%. 

Enamines can be reduced to the corresponding saturated amines by treatment with formic acid. A very simple experimental procedure can be used in which formic acid is added to the neat enamine at such a rate that foaming due to evolution of carbon dioxide can be kept under control. The reduction of the morpholine enamine from camphor was studied in a two-level factorial design in order to determine whether or not an excess of formic acid should be used and at which temperature the reaction should be run. 

The reduction of the morpholine enamine from camphor by the reaction with formic acid was discussed in Chapter 5. In the example below, this reaction was applied to the reduction of the corresponding pyrrolidine enamine. The reaction was conducted without any solvent present, i.e. by adding formic acid dropwise to the hot enamine, and afforded an almost quantitative conversion to the corresponding bornyl pyrrolidine. However, the reaction was not stereoselective and a mixture of endo and exo isomers was formed. The proportions were endo isomer (85 %), exo isomer (15 %). This was regarded as a promising result. 

Catalytic amounts of camphor-10-sulfonic acid (CSA) in methanol and dichloro-methane smoothly cleave the orthoester function in 23, giving the intermediate y-lactone-l,3-diol. Subsequent protection of the primary alcohol function with di-methylphenylchlorosilane (TPSCl) in dimethylformamide with imidazole as the base and of the secondary alcohol function via alcoholate with benzylbromide (BnBr) following WiLLlAMSON s ether synthesis yields the y-lactone 24. Its reduction with lithiumaluminumhydride leads to two vicinal primary alcohol groups. Thereafter, camphor-10-sulfonic acid (CSA) in dichloromethane selectively cleaves the TBS ether and catalyzes the transketalization with acetone dimethyUcetal to the precursor 25 of the aldehyde 8. Smooth oxidation of the primary alcohol function in 25 is achieved with tetrapropylammoniumperruthenate (TPAP) and A-methyl-morpholine-A-oxide (NMO) in acetonitrile. 

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