NOVELTY - Synthesizing chiral 3-substituted tetrahydroquinoline (II) from 4,5 disubstituted o-nitrohydrocinnamaldehyde (I) with high enantioselectivity (99%), comprises, alpha -functionalizing of aldehyde by stirring (I), polar aprotic organic solvent, nitrosobenzene or dialkyl azodicarboxylate in presence of D or L proline at a temperature of -20 degrees C to 30 degrees C for 10 minutes to 4 hours followed by in situ intramolecular reductive cyclization of alpha -functionalized aldehyde by stirring in presence of 10% palladium/carbon/hydrogen (1 atmosphere) and an organic solvent at 20-30 degrees C for 6-12 hours.    USE - The process is useful for preparing (II) (claimed) which is used for preparing therapeutic agents comprising (-) sumanirole and 1-((S)-3-(dimethylamino)-3,4-dihydro-6,7-dimethoxy-quinotin(2H)yl)propan-1-one and for treating Parkinson's disease. No biological data given.    ADVANTAGE - The process: provides (II) with high yield (70-87%), enantiomeric excess (90-99%) (all claimed) and optical purity; utilizes easily available, inexpensive starting material (I); is environmentally friendly, and industrially feasible; and provides (II) that are utilized for synthesis of therapeutically or biologically active ingredient. The process employs organocatalytic alpha -functionalization of aldehydes to generate the requisite chiral center of high optical purities in a single step.    DETAILED DESCRIPTION - Synthesizing chiral 3-substituted tetrahydroquinoline of formula (II) from 4,5 disubstituted o-nitrohydrocinnamaldehyde of formula (I) with high enantioselectivity (99%), comprises, alpha -functionalizing of aldehyde by stirring (I), polar aprotic organic solvent, nitrosobenzene or dialkyl azodicarboxylate in presence of D or L proline at a temperature of -20 degrees C to 30 degrees C for 10 minutes to 4 hours followed by in situ intramolecular reductive cyclization of alpha -functionalized aldehyde by stirring in presence of 10% palladium/carbon/hydrogen (1 atmosphere) and an organic solvent at 20-30 degrees C for 6-12 hours to obtain (II).    Either R, R1 = H, hydroxy-(1-6C)alkyl, halo, aryl, alkylaryl, (1-6C)alkoxy, protecting group such as tert-butyldiphenylsilyl ether, methoxymethyl ether, tosyl, benzyl or tert-butyl carbamate; or    RR1 = -OCH2-O-linkage; and    X = -OH or disubstituted hydrazine-1,2-dicarboxytate of formula (-N-CO2R2-NH-CO2R2); and    R2 = optionally branched (1-6C)alkyl (preferably ethyl, isopropyl, t-butyl) or optionally substituted aryl (preferably 4-chlorobenzyl).