Abstract:
A cyclopropachromen derivative represented by formula (I): ##STR1## The compounds are capable of promoting the extension of nerve dendrites and are useful as improving and treating agents for cerebral organic disorders and psychic function disorders.

Description:
This is a continuation-in-part application of U.S. Ser. No. 07/662,107, filed on Feb. 28, 1991, now abandoned. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a novel cyclopropachromen derivative represented by formula (I) shown below and a pharmaceutically acceptable salt thereof. 
     The compounds according to the present invention have a wide use as improving and treating agents for cerebral organic and functional disorders. 
     BACKGROUND OF THE INVENTION 
     Organic and functional disorders in the human brain which controls high grade mental actions and motor functions are critical diseases that concern not only the physical but also the mental well-being of a person. In a rapidly aging society, the development of effective methods of treating brain disorders as well as therapeutic drugs is of pressing importance. However, despite many years of studies conducted to unravel the functions of the brain, only a partial understanding has so far been achieved and an understanding of individual diseases, still less a comprehensive and systematic knowledge of the brain, has not yet been obtained. 
     While many brain diseases are known today, Alzheimer&#39;s disease (hereinafter sometimes abbreviated as AD) and senile dementia of the Alzheimer&#39;s type (hereinafter sometimes referred to as SDAT), both of which are progressive organic diseases of the brain that are characterized by lowered cognitive capabilities due to the degenerative atrophy of neurocytes in the brain, are becoming major social concerns requiring the implementation of effective care methods since the number of patients suffering from these diseases, especially in industrialized countries is rapidly increasing, and the progression of these diseases results in severe disability and ultimate death for those afflicted. 
     Under these circumstances, industrialized countries are engaged in nationwide projects for the establishment of effective methods for treating AD and SDAT. However, even the causes of the diseases have not been properly elucidated. Only the morphological changes that can be observed in the brain or the biochemical changes as the consequences have been partly unravelled, but no effective therapy has yet been established. 
     Cholinergic agents including choline precursors, cholinesterase inhibitors, etc. are being tested, on the basis of the cholinergic theory, in clinical fields as nosotropic agents for treating AD and SDAT. However, the evaluation on the utility of these therapeutics is varied and no single drug exhibits definite therapeutic effects. 
     Three basic methods may be conceived of to treat neurodegenetative diseases including AD and SDAT: (1) suppressing or preventing the degenerative process of neurons; (2) compensating for the lost function of neurons with a drug; and (3) promoting the plasticity of remaining neurons to form a new neuro-circuit. The aforementioned cholinergic agents and chollnesterase inhibitors are within the class (2) since they are focused on the fact that, in a characteristic pathological symptom of AD and SDAT, cholinergic nerve fascicles that project from the basal forebrain to the cerebral cortex and the hippocampus undergo atrophic degeneration, yet acetylcholine receptors in the cerebral cortex and the hippocampus which are the cells that control those cholinergic nerve fascicles remain in a normal state. These drugs are expected to work effectively in the case of dysfunction of acetylcholine systems but no definite therapeutic effects are anticipated for diseases such as AD and SDAT which cannot be fully explained solely on the basis of the dysfunction of acetylcholine systems. 
     Aggravation of brain diseases could be prevented if the degenerative process of neurons could be suppressed as in (1). If a new neuron network could be formed by promoting the compensatory functional recovery of remaining neurons as in (3), not only could the progress of the diseases be prevented but also positive recovery of neuro-functions could reasonably be expected. 
     A drug that has been proposed in line with these approaches is a nerve growth factor (which is hereinafter referred to as &#34;NGF&#34;). NGF has long been known as a factor that is essential to the existence of sympathetic ganglion and sensory ganglion neurons in the peripheral nervous system, and hence extensive studies have been conducted on NGF. Recently, it has become clear that NGF also takes part in the existence and sustained functions of cholinergic neurons in the basal forebrain which are important to memory and learning. Thus the possibility of using NGF as an effective means of recovering part of the brain functions has been studied. However, NGF is a basic protein having a molecular weight of ca. 27,000 and the efforts to develop a direct method of compensatory therapy using NGF have not yet achieved a prospect for application in clinical fields since they involve many problems to be solved as regards the methods of its production and administration. 
     Under these circumstances, increasing attention has recently been drawn by ganglioside as a non-peptide trophic factor like substance. For example, L. Facci et al. reported in J. Neurochem., 42, 299-305 (1985) that monosialoganglioside (GM 1 ) promoted the formation of nerve dendrites in cultured cells derived from mouse neuroblasts. L. F. Agnati et al., Acta Physiol. Scand., 119, 347-364 (1983) and G. Toffano et al., Brain Res., 296, 233-239 (1984) reported that GM 1  inhibited the degeneration of the cell body of nigra dopamine neurons that occurred after the removal of the cortex on one side of the brain. Further, G. Jonsson et al. reported in Neurosci. Lett. (Suppl.), 14, 185 (1983) that GM 1  worked suppressively on the decrease in 5-HT in the frontal and occipital lobes that was caused by pretreatment with 5,7-dihydroxytriptamine. These reports did not make it clear whether the action of ganglioside was direct or indirect in relation to the intermediary of the neurotrophic factor in NGF but they did show that ganglioside had the ability to either inhibit the degeneration of neurons or promote the compensatory functional recovery of a degenerated nerve circuit. Therefore, these observations suggest the possibility of new pharmaceutical therapy of AD and SDAT. 
     In fact, however, ganglioside is a glycosphingolipid containing sialic acid and GM 1 , too, is a high-molecular weight compound that is the condensate of sialic acid, four saccharides and ceramide. Hence, the use of ganglioside as a drug for treating AD and SDAT involves several problems to be solved in terms of the methods of preparation and administration. 
     SUMMARY OF THE INVENTION 
     Under these circumstances, the present inventors conducted intensive studies and found novel compounds that were easy-to-synthesize. They are low molecular weight compounds that are capable of promoting the extension of nerve dendrites and that are as effective as NGF and ganglioside in suppressing the degenerative process of nerves or regenerating a damaged nerve network to promote the recovery of its functions. 
     Further, the novel cyclopropachromen derivatives of the present invention exhibit cerebral function improving activities in experimental model animals suffering from various cerebral anoxemic conditions even at low dose levels and are, therefore, effective in alleviating and treating organic and functional disorders. 
     The present invention provides a cyclopropachromen derivative represented by formula (I): ##STR2## wherein n represents an integer of 2 to 5; 
     one of R 1  and R 2  represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, a phenyl group or an aralkyl group having 7 to 10 carbon atoms, and the other of R 1  and R 2  represents an alkyl group having 1 to 5 carbon atoms, a phenyl group or an aralkyl group having 7 to 10 carbon atoms, or 
     R 1  and R 2  form together with the nitrogen atom, to which they are attached, a morpholino group, a thiomorpholino group, pyrrolidinyl group, a piperidinyl group, a homopiperidinyl group, a piperazinyl group, a homopiperazinyl group, an N-alkylpiperazinyl group, N-alkylhomopiperazinyl group, an N-hydroxyalkylpiperazinyl group or a pyrrolidonyl group or alternatively R 1  and R 2  form together with the nitrogen atom to which they are attached, and further a carbon atom to which said nitrogen atom is bound, a pyrrolitydinyl group of formula: ##STR3## A 1  and A 2  independently represent a hydroxyl group, a halogen atom, an alkoxy group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms substituted with phenyl or pyridyl; 
     B 1  and B 2  independently represent a hydrogen atom, a hydroxyl group, a halogen atom, an alkoxy group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms substituted with phenyl or pyridyl, and a pharmaceutically acceptable salt thereof. 
     The term &#34;halogen&#34; as used herein includes fluoro, chloro, bromo or iodo, and fluoro, chloro and bromo are preferred. 
     The integer represented by n is preferably 2-4 and more preferably 2 or 3. 
     Examples of the alkyl group represented by R 1  and R 2  may be straight or branched. Those having 1-3 carbon atoms such as methyl and ethyl are preferred. 
     Examples of the aralkyl group represented by R 1  and R 2  include benzyl, phenethyl. 
     When R 1  and R 2  form together with the nitrogen atom, to which they are attached, an N-alkylpiperazinyl group or an N-hydroxyalkylpiperazinyl group, examples of the alkyl moiety include methyl, ethyl and propyl. 
     When A 1 , A 2 , B 1  and B 2  represent an alkoxy group, it has preferably 1 to 5 carbon atoms. 
     It should be understood that the compound of the present invention comprises several isomers as schematically illustrated below. Namely, there are two geometrical isomers (E-form and Z-form) at the oxime structure, and further, each of the geometrical isomers has two optical isomers. Each isomers can be separated by a conventional manner by way of, e.g. recrystallization, column chromatography, TLC, HPLC or by using a chemical substance commonly used in the separation of optical isomers. ##STR4## 
     DETAILED DESCRIPTION OF THE INVENTION 
     The compounds represented by formula (I) can be synthesized in accordance with the process described in Japanese Patent Application Laid-Open No. Sho-62-198676 as illustrated by the following reaction scheme: ##STR5## 
     Compound (II) is reacted with hydroxylamine hydrochloride in pyridine to obtain compound (III). Compound (III) is then condensed with a halogenated amine compound of formula: ##STR6## wherein R 1 , R 2  and n are as defined above; and X represents a halogen atom, to obtain compound (I). 
     Alternatively, compound (III) is condensed with a bifunctional compound represented by formula: 
     
         X.sup.1 --(CH.sub.2).sub.n --X.sup.2 
    
     wherein X 1  represents a halogen atom; and X 2  represents a halogen atom or an ethylene oxide group, to form compound (IV), which is then reacted with an appropriate amine compound to obtain compound (I). 
     The starting compound (II) is known per se as disclosed in P. Bennett, et al., J. Chem. Soc., Perkin Trans., I, No. 12, p. 2990 (1979) or can be synthesized by the process disclosed therein. 
     The compounds according to the present invention have low toxicity and can be formulated either as such or as a salt thereof, such as inorganic acid salts (e.g., hydrochloride, sulfate, nitrate, phosphate), organic acid salts (e.g., acetate, propionate, butyrate, tartrate, malonate, succinate, maleate, fumarate, oxalate, citrate, malate, p-toluenesulfonate, methanesulfonate), and alkali metal salts (e.g., sodium salt, potassium salt) in cases where either A 1  or A 2  is a hydroxyl group, together with known carriers into various preparations for the improvement and treatment of symptoms caused by various disturbances in the brain. For example, the active ingredient is formulated either alone or in combination with commonly employed vehicles, etc. into appropriate dosage forms for oral or non-oral administration, such as capsules, tablets, injectable solutions, etc. 
     These preparations can be prepared, for example, as follows. Capsules are prepared by mixing a powdered active ingredient with vehicles, e.g., lactose, starch or a derivative thereof, a cellulose derivative, etc., and charging the mixture in gelatin capsules. Tablets are prepared by mixing the active ingredient with the abovementioned vehicles and, in addition, binders, e.g., sodium carboxymethyl cellulose, alginic acid, gum arabic, etc., and water, granulating the mixture if desired, adding lubricants, e.g., talc, stearic acid, etc., to the mixture, and punching the mixture by means of a conventional compressive punching machine. Injectable solutions for non-oral administration are prepared by dissolving the active ingredient in sterilized distilled water or sterilized physiological saline together with dissolving aids and sealing the solution into ampules. If desired, the injectable solutions may contain stabilizers, buffering agents, and so on. 
    
    
     Synthesis of the compounds according to the present invention will be illustrated below by way of Reference Examples and Examples. Reference Examples relate to preparation of starting compounds to be used in the synthesis of the compounds of formula (I). Reference Examples are referred to with a combination of two numbers, in which the first number corresponds to the above-mentioned formula (II) to (IV) [e.g., Reference Example II-1 relates to preparation of compound (II)]. 
     Reference Example II-1 
     1a, 7a-dihydro-4,5-dimethoxy-1-phenylcyclopropa[b]chromen-7-(1H)-one ##STR7## 
     In 100 ml of dimethyl sulfoxide was dissolved 6.78 g (30.8 mmol) of trimethylsulfoxonium iodide, and 1.24 g (30.8 mmol) of sodium hydride (60% oil dispersion) was added to the solution in small portions. The mixture was stirred until evolution of hydrogen ceased. A dimethyl sulfoxide solution having dissolved therein 5.82 g (20.5 mmol) of 6,7-dimethoxyflavone was then added to the reaction mixture, followed by stirring at room temperature for 4 hours. The reaction mixture was poured into ice-water and extracted with diethyl ether. The extract was washed with water and dried over anhydrous magnesium sulfate. After filtration, the filtrate was concentrated, and the residue was purified by silica gel column chromatography using a mixed solvent of hexane-ethyl acetate (70:30) as an eluent to obtain 2.72 g (yield: 44.8%) of the titled compound. 
     Reference Examples II-2 to II-4 
     The following compounds were synthesized in the same manner as in Reference Example II-1. 
     1a,7a-dihydro-3,4-dimethoxy-1a-phenylcylopropa[b]chromen-7(1H)-one (Reference Example II-2); 
     4,5-dichloro-1a,7a-dihydro-1a-phenylcyclopropa[b]chromen-7(1H)-one (Reference Example II-3); 
     4,5-dibenzyloxy-1a,7a-dihydro-1a-phenylcylopropa[b]chromen-7(1H)-one (Reference Example II-4). 
     Physical properties of the compounds obtained in Reference Examples II-1 through II-4 are shown in Table 1 below. 
     
                                           TABLE 1__________________________________________________________________________ReferenceExample Structure                  m.p. (°C.)                                  IR      NMR__________________________________________________________________________II-1  ##STR8##                  146-149                                  3000 2940 1665 1610 1500 1470 1455                                  1420 1380 1280 1200 1165 1080 1030                                  000  960  810  755  695                                          1.66(t, 1H, J=6.6Hz)                                          2.01(dd, 1H, J=6.6Hz &amp;                                          10.6Hz) 2.47(dd, 1H,                                          J=6.6Hz &amp; 10.6Hz) 3.90(s,                                          3H), 3.71(s, 3H)  6.52(s,                                          1H) 7.31-7.49(m, 6H)II-2  ##STR9##                  105-112                                  2920 1670(br) 1625(br) 1595 1498                                  1440 1420 1350 1280 1260 1120 1080                                   995  780                                          1.73(t, 1H, J=6.6Hz),                                          2.00-2.08(m, 1H) 2.50(dd,                                          1H, J=6.6Hz &amp; 10.9Hz)                                          3.90(s, 3H), 3.94(s, 3H)                                          6.71(d, 1H, J=8.6Hz)                                          7.3-7.5(m, 5H) 7.71 (d,                                          1H, J=8.6Hz)II-3  ##STR10##                 108-115                                  1675 1598 1550 1445 1405 1260 1220                                  1120  975  940  890  855  830                                          1.54(t, 1H, J=6.6Hz)                                          2.10(dd, 1H, J=6.6Hz &amp;                                          10.6Hz) 2.53(dd, 1H,                                          J=6.6Hz &amp; 10.6Hz) 7.21(s,                                          1H), 7.3-7.5(m, 5H)                                          8.00(s, 1H)II-4  ##STR11##                 124-125                                  1660 1610 1500 1445 1370 1270 1200                                  1080 1000  865  820  760  740                                          1.64(t, 1H, J=6.6Hz)                                          1.99(dd, 1H, J=6.6Hz &amp;                                          10.6Hz) 2.44(dd, 1H,                                          J=6.6Hz &amp; 10.6Hz) 5.15(s,                                          2H), 5.18(s, 2H) 6.56(s,                                          1H)  7.28-7.49(m,__________________________________________________________________________                                          16H) 
    
     Reference Example III-1 
     1a, 7a-dihydro-4,5-dimethoxy-7 (1H)-hydroxyimino-1a-phenylcyclopropa[b]chromen ##STR12## 
     In 50 ml of pyridine was dissolved 500 mg (1.69 mmol) of the compound obtained in Reference Example II-1, and 469 mg (6.76 mmol) of hydroxylamine hydrochloride was added thereto, followed by stirring at 100° C. for 1 hour. The reaction mixture was concentrated, diluted with water, and extracted with chloroform. The chloroform extract was washed with water and dried over anhydrous magnesium sulfate. After filtration, the filtrate was concentrated, and the residue was purified by silica gel column chromatography using a mixed solvent of hexane-ethyl acetate (2:1 by volume) as an eluent to obtain 492 mg (93.6%) of the titled compound. 
     Reference Examples III-2 to III-4 
     The following compounds were synthesized in the same manner as in Reference Example III-1. 
     1a,7a-dihydro-3,4-dimethoxy-7(1H)-hydroxyimino-1a-phenylcyclopropa[b]chromen (Reference Example III-2); 
     4,5-dichloro-1a,7a-dihydro-7(1H)-hydroxyimino-1a-phenylcyclopropa[b]chromen (Reference Example III-3); 
     4,5-dibenzyloxy-1a,7a-dihydro-7(1H)-hydroxyimino-1a-phenylcyclopropa[b]chromen (Reference Example III-4). 
     Physical properties of the compounds obtained in Reference Examples III-1 through III-4 are shown in Table 2 below. 
     
                                           TABLE 2__________________________________________________________________________ReferenceExample Structure                  m.p. (°C.)                                  IR      NMR__________________________________________________________________________III-1  ##STR13##                 194-195                                  3200 2820 1615 1505 1440 1420 1380                                  1305 1255 1210 1160 1080 1035 1010                                   900  840  765  690                                          1.60(t, 1H, J=6.6Hz)                                          2.13(dd, 1H, J=6.6Hz &amp;                                          10.6Hz) 2.92(dd, 1H,                                          J=6.6Hz &amp; 10.6Hz) 3.89(s,                                          3H), 3.92(s, 3H) 6.56(s,                                          1H)  7.27-7.58(m, 6H)III-2  ##STR14##                 152-153                                  3200 2910 1640 1600 1495 1450(br)                                  1422 1375 1335 1280 1255 1220 1140                                  1105 1090 1015  960  855  825  750                                   715    1.66(t, 1H, J=6.6Hz)                                          1.92(dd, 1H, J=6.6Hz &amp;                                          10.6Hz) 3.14(dd, 1H,                                          J=6.6Hz &amp; 10.6Hz) 3.89(s,                                          6H) 6.62(d, 1H) 7.25-7.55                                          (m, 5H) 7.77(m, 1H)III-3  ##STR15##                 136.5-137.5                                  1625 1405 1200(br)                                          1.60(t, 1H, J=6.6Hz)                                          1.94(dd, 1H, J=6.6Hz &amp;                                          10.6Hz) 3.08(dd, 1H,                                          J=6.6Hz &amp; 10.6Hz) 7.13(s,                                          1H) 7.25-7.5(m, 5H)                                          7.87(s, 1H)III-4  ##STR16##                 160-161                                  3100 2850 1610 1500 1440 1375 1300                                  1250 1200 1170 1080 1040 1000  930                                   900  840  750  690                                          1.62(t, 1H, J=6.6Hz)                                          2.08(dd, 1H, J=6.6Hz &amp;                                          10.5Hz) 2.90(dd, 1H,                                          J=6.6Hz &amp; 10.5Hz 5.06(s,                                          2H), 5.12(s, 2H) 6.57 (s,                                          1H) 7.22-7.54(m,__________________________________________________________________________                                          16H) 
    
     Reference Example IV-1 
     7(1H)-(2-chloroethyloxymino)-4,5-dimethoxy-1a,7a-dihydro-1a-phenylcycopropa[b]chromen ##STR17## 
     In 20 ml of dioxane was dissolved 300 mg of the compound obtained in Reference Example III-1, and 57.9 mg (1.5 equivalents) of sodium hydride (60% oil dispersion) was added to the solution. Then, 0.482 ml (6 equivalents) of 1-bromo-2-chloroethane was added thereto, and the reaction mixture was heated at 100° C. for 5 hours with stirring, followed by concentration. The residue was diluted with water and extracted with diethyl ether. The diethyl ether layer was washed with water and dried over anhydrous magnesium sulfate. After filtration, the filtrate was concentrated, and the residue was purified by silica gel column chromatography using a mixed solvent of hexane and ethyl acetate (85:15 by volume) as an eluent to obtain 275 mg (76.3%) of the titled compound. 
     Reference Example IV-2 
     7(1H)-(3-chloropropyloxyimino)-4,5-dimethoxy-1a,7a-dihydro-1a-phenylcyclopropa[b]chromen 
     The titled compound was synthesized from the compound of Reference Example III-1 in the same manner as in Reference Example IV-1. 
     Physical properties of the compounds obtained in Reference Examples IV-1 and IV-2 are shown in Table 3 below. 
     
                                           TABLE 3__________________________________________________________________________ReferenceExample Structure             m.p. (°C.)                             IR    NMR__________________________________________________________________________IV-1  ##STR18##            oil   2950 2840 1605 1500 1455 1425 1260 1220                             200 1170 1085 1035  860  805  760                                   1.57(t, 1H, J=6.6Hz) 1.89(dd, 1H,                                   J=6.6Hz &amp; 10.6Hz) 3.02(dd, 1H,                                   J=6.6Hz &amp; 10.6Hz) 3.81(t, 2H,                                   J=5.9Hz) 3.87(s, 3H), 3.90(s, 3H)                                   .40(t, 2H, J=5.9Hz) 6.50(s, 1H)                                   7.21-7.49(m, 6H)IV-2  ##STR19##            oil   2920 1620 1600 1500 1465 1450 1420 1370                             300 1255 1210 1195 1160 1080 1035   865                              805  755  690                                   1.56(t, 1H, J=6.6Hz) 1.87(dd, 1H,                                   J=6.6Hz &amp; 10.5Hz 2.22(quintet1,                                   2H, J=6.6Hz) 2.94(dd, 1H, J=6.6Hz                                   &amp; 10.5Hz) 3.69(t, 2H, J=6.6Hz)                                   3.87(s, 3H), 3.90(s, 3H) 4.32(t,                                   2H, J=6.6Hz) 6.49(s,                                   1H) 7.23-7.48(m,__________________________________________________________________________                                   6H) 
    
     Example 1 
     1a,7a-dihydro-4,5-dimethoxy-7(1H)-(2-methylaminoethyloxyimino)-1a-phenylcyclopropa[b]chromen [Compound of formula (I) wherein A 1  =4-OCH 3  ; A 2  =5-OCH 3  ; B 1  =H; B 2  =H; NR 1  R 2  =NHCH 3  ; and n=2] ##STR20## 
     In 10 ml of dioxane was dissolved 270 mg of the compound obtained in Reference Example IV-1, and 10 ml of a saturated mono-methylamine solution in dioxane was added to the solution. The mixture was heated in a closed tube at 100° C. for 17 hours and then freed of dioxane by distillation. Water and a sodium hydroxide aqueous solution were added to the residue, and the residue was extracted with methylene chloride. The extract was washed with water and dried over magnesium sulfate. After filtration, the filtrate was concentrated, and the residue was purified by silica gel column chromatography using a mixed solvent of methylene chloride and methanol (9:1) as an eluent to obtain 165 mg (62.0%) of the titled compound. 
     The resulting compound was converted to its L-tartrate in a usual manner. 
     Example 2 
     4,5-dichloro-1a,7a-dihydro-7(1H)-(2-dimethylaminoethyloxyimino)-1a-phenylyclopropa[b]chromen [Compound of formula (I) wherein A 1  =4-Cl; A 2  =5-Cl; B 1  =H, B 2  =H; NR 1  R 2  =N(CH 3 ) 2  ; and n=2] ##STR21## 
     In 7 ml of tetrahydrofuran was dissolved 95 mg (0.3 mmol) of the compound obtained in Reference Example III-3, and 18 mg (0.45 mmol) of sodium hydride (60% oil dispersion) was added thereto, followed by stirring at room temperature for 45 minutes. To the reaction mixture was added 128 mg (1.19 mmol) of dimethylaminoethyl chloride, followed by refluxing under heating for 17 hours. The reaction mixture was concentrated, and the residue was diluted with ice-water and extracted with diethyl ether. The extract was washed with water and dried over anhydrous magnesium sulfate. After filtration, the filtrate was concentrated, and the residue was purified by neutral silica gel column chromatography using a mixed solvent of methylene chloride and methanol (95:5) as an eluent to obtain 112 mg (99.0%) of the titled compound. 
     The resulting compound was converted to its maleate in a usual manner. The physical properties of the maleate are shown in Table 4 below. 
     Example 3 
     1a,7a-dihydro-4,5-dimethoxy-7(1H)-(2-dimethylaminoethyloxyimino)-1a-phenylcyclopropa[b]chromen [Compound of formula (I) wherein A 1  =4-OCH 3  ; A 2  =5-OCH 3  ; B 1  =H; B 2  =H; NR 1  R 2  =N(CH 3 ) 2  ; n=2] 
     The titled compound was synthesized from the compound of Reference Example III-1 in the same manner as in Example 2. 
     Example 4 
     7(1H)-2-(diethylaminoethyloxyimino)-1a,7a-dihydro-4,5-dimethoxy-1a-phenylcyclopropa[b]chromen [Compound of formula (I) wherein A 1  =4-OCH 3  ; A 2  =5-OCH 3  ; B 1  =H; B 2  =H; NR 1  R 2  =N(C 2  H 5 ) 2  ; n=2] 
     The titled compound was synthesized from the compound of Reference Example III-1 in the same manner as in Example 2. 
     Example 5 
     4,5-dichloro-1a,7a-dihydro-7(1H)-(3-methylaminopropyloxyimino)-1a-phenylcyclopropa[b]chromen [Compound of formula (I) wherein A 1  =4-Cl; A 2  =5-Cl; B 1  =H; B 2  =H; NR 1  R 2  =NHCH 3  ; n=3] 
     The titled compound was synthesized from the compound of Reference Example III-3 in the same manner as in Example 2. 
     Example 6 
     1a,7a-dihydro-4,5-dimethoxy-7(1H)-(3-methylaminopropyloxyimino)-1a-phenylcyclopropa[b]chromen [Compound of formula (I) wherein A 1  =4-OCH 3  ; A 2  =5-OCH 3  ; B 1  =H; B 2  =H; NR 1  R 2  =NHCH 3  ; n=3] 
     The titled compound was synthesized from the compound of Reference Example IV-2 in the same manner as in Example 1. 
     Example 7 
     4,5-dichloro-1a,7a-dihydro-7(1H)-(3-ethylaminopropyloxyimino)-1a-phenylcyclopropa[b]chromen [Compound of formula (I) wherein A 1  =4-Cl; A 2  =5-Cl; B 1  =H; B 2  =H; NR 1  R 2  =NHC 2  H 5  ; n=3] 
     The titled compound was synthesized from the compound of Reference Example III-3 in the same manner as in Example 2. 
     Example 8 
     1a,7a-dihydro-7(1H)-(3-dimethylaminopropyloxyimino)-3,4-dimethoxy-1a-phenylcyclopropa[b]chromen [Compound of formula (I) wherein A 1  =3-OCH 3  ; A 2  =4-OCH 3  ; B 1  =H; B 2  =H; NR 1  R 2  =N(CH 3 ) 2  ; n=3] 
     The titled compound was synthesized from the compound of Reference Example III-2 in the same manner as in Example 2. 
     Example 9 
     4,5-dichloro-1a,7a-dihydro-7(1H)-(3-dimethylaminopropyloxyimino)-1a-phenylcyclopropa[b]chromen [Compound of formula (I) wherein A 1  =4-Cl; A 2  =5-Cl; B 1  =H; B 2  =H; NR 1  R 2  =N(CH 3 ) 2  ; n=3] 
     The titled compound was synthesized from the compound of Reference Example III-3 in the same manner as in Example 2. 
     Example 10 
     1a,7a-dihydro-4,5-dimethoxy-7(1H)-(3-dimethylaminopropyloxyimino)-1a-phenylcyclopropa[b]chromen [Compound of formula (I) wherein A 1  =4-OCH 3  ; A 2  =5-OCH 3  ; B 1  =H; B 2  =H; NR 1  R 2  =N(CH 3 ) 2  ; n=3] 
     The titled compound was synthesized from the compound of Reference Example III-1 in the same manner as in Example 2. 
     Example 11 
     4,5-dibenzyloxy-1a,7a-dihydro-7(1H)-(3-dimethylaminopropyloxyimino)cyclopropa[b]chromen [Compound of formula (I) wherein A 1  =4-OCH 2  -C 6  H 5  ; A 2  =5-OCH 2  -C 6  H 5  ; B 1  =H; B 2  =H; NR 1  R 2  =N(CH 3 ) 2  ; n=3] 
     The titled compound was synthesized from the compound of Reference Example III-4 in the same manner as in Example 2. 
     Example 12 
     1a,7a-dihydro-4,5-dihydroxy-7(1H)-(3-dimethylaminopropyloxyimino)cyclopropa[b]chromen [Compound of formula (I) wherein A 1  =4-OH; A 2  =5-OH; B 1  =H; B 2  =H; NR 1  R 2  =N(CH 3 ) 2  ; n=3] 
     In 20 ml of ethyl acetate was suspended 48 mg of 10% palladium-on-carbon. After displacing the atmosphere with hydrogen by suction, 240 mg of the compound obtained in Example 11 was added to the suspension, and the mixture was stirred at room temperature for 5 hours in a hydrogen stream (atmospheric pressure). The reaction mixture was worked-up in the same manner as in Example 2 to obtain 67.0 mg (41.5%) of the titled compound. 
     Physical properties of the compounds obtained in Examples 1 to 12 are shown in Table 4 below. 
     
         TABLE 4  Example Structure m.p. (°C.) IR NMR Elementary Analysis/MS    1  ##STR22##  88-89(L-tartrate) 2930 28401600 15001455 14201380 13101260 12151165     1 1080040  860 800  755 695 1.57(t, 1H, J=6.6Hz)1.88(dd, 1H, J=6.6Hz &amp; 10.6Hz)2.49(s, 3H), 2.94(t, 2H, J=5.1Hz)2.97(dd, 1H, J=6.6Hz &amp; 10.6Hz)3.8 7(s, 3H), 3.89(s, 3H)4.31(t, 2H, J=5.1Hz)6.49(s, 1H)7.22-7.49(m, 6H)  ##STR23##  2 ##STR24##  177-179(Maleate) 2940 28202760 16151465 14021280 12351122 1035 988  885 7 60  742 1.45-1.55(m, 1H)1.90(dd, 1H, J=6.6Hz &amp; 10.6Hz)2.31(s, 6H) 2.69(t, 2H, J=6.1Hz)2.99(dd, 1H, J=6.6Hz &amp; 10.6Hz)4.25-4.35(m, 2H) 7.10(s, 1H)7.3-7.45(m, 5H) 7.91(s, 1H)  ##STR25##  3 ##STR26##  122-125(Maleate) 2920 28002750 16001500 14451415 12501205 11901160 10801030  860 800  750 690 1.55(t, 1H, J=6.6Hz)1.85(dd, 1H, J=6.6Hz &amp; 10.6Hz)2.32(s, 6H), 2.70(t, 2H, J=5.9Hz)2.99(dd, 1H, J=6.6Hz &amp; 10.6Hz)3.8 6(s, 3H), 3.89(s, 3H)4.30(t, 2H, J=5.9Hz)6.49(s, 1H)7.25-7.47(m, 6H)  ##STR27##  4 ##STR28##  156-157(Citrate) 2950 28101615 16001500 14601450 14201255 12101080 1035 9 70  860 800  755 690 1.07(t, 6H, J=7.3Hz)1.55(t, 1H, J=6.6Hz)1.85(dd, 1H, J=6.6Hz &amp; 10.6Hz)2.66(quartett, 4H, J=7.3Hz)2.88(t, 2H, J=6.2Hz)2.98( dd, 1H, J=6.6Hz &amp; 10.6Hz)3.86(s, 3H), 3.89(s, 3H)4.31(t, 2H, J=6.2Hz) 6.49(s, 1H)7.24-7.47(m, 6H)  ##STR29##  5 ##STR30##  (Fumarate)100-105 3435 29552790 16851615 14051285 12401130  985 760 745 705 1.59(br. 1H)1.95(m, 3H)2.45(s, 3H)2.72(t, 2H, J=7.3Hz)2.96(dd, 1H, J=6.6Hz &amp; 10.6Hz)4.27(m, 2H)7.10(s, 1H)7.4(m, 5H)7.91(s, 1H)  ##STR31##  6 ##STR32##  110-115(L-tartrate) 2920 16001500 14601445 14201365 13001255 12051190 11601080 1040 985  860 800  755 720  690 1.56(t, 1H, J=6.6Hz)1.87(dd, 1H, J=6.6Hz &amp; 10.6Hz)1.94(quintett, 2H, J=6.6Hz)2.44(s, 3H), 2.73(t, 2H, J=6.6Hz)2.96(dd, 1H, J=6.6Hz &amp; 10.6Hz)3.86(s, 3H), 3.89(s, 3H),4.25(t, 2H, J=6.6Hz)6.49(s, 1H)7.23-7.48(m, 7H)  ##STR33##  7 ##STR34##  (Fumarate)137-140 3435 29452790 16901615 14051285 12401130  985 760 745 700 1.10(t, 3H, J=7.3Hz) 1.52(br, 1H)1.57(t, 1H, J=6.6Hz) 1.9(m, 3H)2.66(q, 2H, J=7.3Hz)2.76(t, 2H, J=7.3Hz)2.96(dd, 1H, J=6.6Hz &amp;        4 10.6Hz).27(m, 2H ) 7.10(s, 1H)7.4(m, 5H) 7.91(s, 1H)  ##STR35##  8 ##STR36##  85-90(Citrate) 2940 16001500 14501420 13801345 12851225 10951030  960 795  750 720  690 1.62(t, 1H, J=6.6Hz)1.8-2.0(m, 3H) 2.25(s, 6H)2.25-2.45(m, 2H)3.02(d d, 1H, J=6.6Hz &amp; 10.6Hz)3.88(s, 6H) J=6.3Hz)4.15-4.3(m, 2H) 6.60(d, 1H, J=9.2Hz)7.25-7.6(m, 6H)  ##STR37##  9 ##STR38##  181-184(Maleate) 2940 16151462 14021280 12351122 1040 985 1.5-1.65(m, 1H)1.85-2.0(m, 3H)2.27(s, 6H)2.97(dd, 1H, J=6.6Hz &amp; 10.6Hz)2.40(t, 2H, J=7.3Hz)4.24(t, 2H) 7.10(s, 1H)7.3-7.45(m, 5H)7.91(s, 1H)  ##STR39##   10  ##STR40##  131.0-132.5(Maleate) 2950 28602820 27701605 15051465 14201375 13101260 12151200  1160 970  865 805  760 695 1.57(t, 1H, J=6.6Hz)1.90(dd, 1H, J=6.6Hz &amp; 10.6Hz)2.30-2.40(m, 2H) 2.78(s, 6H)2.89( dd, 1H, J=6.6Hz &amp; 10.6Hz)3.09-3.18(m, 2H)3.87, 3.90(s, 3H)4.28(t, 2H, J=5.7Hz) 6.50(s, 1H)7.19(s, 1H)7.32-7.49(m, 5H)  ##STR41##   11  ##STR42##  oil 2930 28602800 27601600 15001440 13701300 12551200 11651080 10351020  900 850  735  690 1.55(t, 1H, J=6.6Hz)1.84(dd, 1H, J=6.6Hz &amp; 10.6Hz)1.96(quintett, 2H, J=7.0Hz)2.30(s, 6H) 2.50(t, 2H, J=7.0Hz) 2.93(dd, 1H, J=6.6Hz &amp; 10.6Hz)4.21(t, 2H, J=7.0Hz)5.09(s, 4H) 6.55(s, 1H)7.25-7.48(m, 16H) MS448  12  ##STR43##  oil 3350 29401600 15001450 13801250 11601115 10601015  980 900  870 810  755 725  695 1.58(t, 1H, J=6.6Hz)1.83(dd, 1H, J=6.6Hz &amp; 10.5Hz)2.00-2.12(m, 2H), 2.66(s, 6H)2.88(dd, 1H, J=6.6Hz &amp; 10.5Hz)2.97-3.03(m, 2H)4.17- 4.25(m, 2H) 6.51(s, 1H)7.27-7.44(m, 6H) MS368 (M.sup.+) 
    
     Test Example 
     The compound of the present invention was capable of promoting the extension of nerve dendrites as observed when it was added to a culture cells (NG108-15). Furthermore, it effectively alleviated the defects concerning directional cognition as observed in a model system by performance after the compound had been given to rats suffering from focal resion in the brain, by injection of AF64A into the basal of their forebrain. These effects of the compound of the present invention have been confirmed by the following tests. 
     (1) Effect of Promoting the Extension of Nerve Dendrites 
     Method 
     The effect on the extension of nerve dentrites was examined in accordance with a method reported by Nakagawa et al. [Brain Res., 439, 11-18 (1988)]. A specimen was added to NG108-15 cells which had been cultured in Dulbecco&#39;s minimum essential medium (DMEM) containing 5% fetal calf serum at 37° C. under 10% CO 2 . Three days later, the extension of nerve dendrites was observed under a phase-contrast microscope. 
     Results 
     Among the test compounds, those produced in Examples 1, 5, 10, and 12 showed an effect of promoting the extension of nerve dendrites when examined at a concentration of from 1 to 15 μM.