NOVELTY - (2R,5R)-4-(benzyloxy)-5-hydroxy-dihydrospiro(oxane-2,2'-pyrrolooxazine)-7'-carbaldehyde (XII) or (2S,5R)-4-(benzyloxy)-5-hydroxy-dihydrospiro(oxane-2,2'-pyrrolooxazine)-7'-carbaldehyde (XV) prepared using (2S,3S,5R)-4,5-bis(benzyloxy)-3-(((methylsulfanyl)methanethioyl)oxy)-dihydrospiro(oxane-2,2'-pyrrolooxazine)-7'-carbaldehyde (XI) or (2R,3S,5R)-4,5-bis(benzyloxy)-3-(((methylsulfanyl)methanethioyl)oxy)-dihydrospiro(oxane-2,2'-pyrrolooxazine)-7'-carbaldehyde (XIV) is subjected to benzyl removal reaction, to obtain rape pollen alkali A (XVI) or caper alkali B (XVII).    USE - Synthesis of rape pollen alkali A or caper alkali B used in preparation of antiinflammatory agents and antiaging drugs.    ADVANTAGE - The method enables economical synthesis of rape pollen alkali A or caper alkali B with high productivity by environmentally-friendly process.    DETAILED DESCRIPTION - A leaving group in 2,3,4,5-diacetone fructose is esterified, to obtain ((2S,6S,9R)-4,4,11,11-tetramethyl-3,5,7,10,12-pentaoxatricyclo(7.3.0.02,6)dodecan-6-yl)methyl-4-methylbenzene-1-sulfonate of formula (I). Compound (I) is subjected to pyrrole nucleophilic substitution reaction in presence of dimethyl formamide or toluene as solvent and sodium hydride, potassium hydroxide or sodium hydroxide as base at 100-150 degrees C, to obtain 1-(((2S,6S,9R)-4,4,11,11-tetramethyl-3,5,7,10,12-pentaoxatricyclo(7.3.0.02,6)dodecan-6-yl)methyl)-1H-pyrrole of formula (II). Compound (II) is reacted with hydroxymethylation agent in formaldehyde solution at 20-120 degrees C in presence of potassium carbonate, sodium carbonate or calcium carbonate as base and water, ethanol and/or methanol as solvent, to obtain (5-(hydroxymethyl)-1-(((2S,6S,9R)-4,4,11,11-tetramethyl-3,5,7,10,12-pentaoxatricyclo(7.3.0.02,6)dodecan-6-yl)methyl)-1H-pyrrol-2-yl)methanol of formula (III). Compound (III) is subjected to oxidation in presence of acetone, ethyl acetate or dimethylsulfoxide as solvent and manganese dioxide, chromium oxide or periodate as oxidizing agent at 20-50 degrees C, to obtain 1-(((2S,6S,9R)-4,4,11,11-tetramethyl-3,5,7,10,12-pentaoxatricyclo(7.3.0.02,6)dodecan-6-yl)methyl)-1H-pyrrole-2,5-dicarbaldehyde of formula (IV). Compound (IV) is deprotected, to obtain 1-(((3aS,6R,7aS)-6,7-dihydroxy-2,2-dimethyl-hexahydro-(1,3)dioxolo(4,5-b)pyran-3a-yl)methyl)-1H-pyrrole-2,5-dicarbaldehyde of formula (V). Compound (V) is reacted with neopentyl glycol in presence of dichloromethane and p-toluenesulfonic acid, sulfuric acid or hydrochloric acid at room temperature or in an ice bath, to obtain 1-(((3aS,6R,7aS)-6,7-dihydroxy-2,2-dimethyl-hexahydro-(1,3)dioxolo(4,5-b)pyran-3a-yl)methyl)-5-(5,5-dimethyl-1,3-dioxan-2-yl)-1H-pyrrole-2-carbaldehyde of formula (VI). Compound (VI) is subjected to benzylation reaction in presence of dimethyl formamide or dichloromethane as solvent and benzyl chloride or benzyl bromide as benzylation reagent at 20-60 degrees C, to obtain 1-(((3aS,6R,7aS)-6,7-bis(benzyloxy)-2,2-dimethyl-hexahydro-(1,3)dioxolo(4,5-b)pyran-3a-yl)methyl)-5-(5,5-dimethyl-1,3-dioxan-2-yl)-1H-pyrrole-2-carbaldehyde of formula (VII). Compound (VII) is acid catalyzed in presence of trifluoroacetic acid and water at room temperature in an aqueous solution of acetic acid, to obtain 1-(((2R,3S,5R)-4,5-bis(benzyloxy)-2,3-dihydroxyoxan-2-yl)methyl)-1H-pyrrole-2,5-dicarbaldehyde of formula (VIII). Compound (VIII) is reacted with sodium borohydride, lithium aluminum hydride or triacetoxy sodium borohydride as reducing agent in methanol, ethanol or mixture of tetrahydrofuran and water, to obtain 1-(((2R,3S,5R)-4,5-bis(benzyloxy)-2,3-dihydroxyoxan-2-yl)methyl)-5-(hydroxymethyl)-1H-pyrrole-2-carbaldehyde of formula (IX). Compound (IX) is subjected to ring closure reaction in presence of toluene sulfonic acid, amino acid, camphor sulfonic acid, hydrochloric acid or sulfuric acid, and dichloromethane, to obtain (2S,3S,5R)-4,5-bis(benzyloxy)-3-hydroxy-1',4'-dihydrospiro(oxane-2,2'-pyrrolo(2,1-c)(1,4)oxazine)-7'-carbaldehyde of formula (X) or (2S,3S,5R)-4,5-bis(benzyloxy)-3-hydroxy-1',4'-dihydrospiro(oxane-2,2'-pyrrolo(2,1-c)(1,4)oxazine)-7'-carbaldehyde of formula (XIII). Compound (X) or (XIII) is subjected to Barton-McCombie deoxidation reaction in tetrahydrofuran and sodium hydride, carbon disulfide or methyl iodide, and separation and purification reactions are carried out, to obtain (2S,3S,5R)-4,5-bis(benzyloxy)-3-(((methylsulfanyl)methanethioyl)oxy)-1',4'-dihydrospiro(oxane-2,2'-pyrrolo(2,1-c)(1,4)oxazine)-7'-carbaldehyde of formula (XI) or (2R,3S,5R)-4,5-bis(benzyloxy)-3-(((methylsulfanyl)methanethioyl)oxy)-1',4'-dihydrospiro(oxane-2,2'-pyrrolo(2,1-c)(1,4)oxazine)-7'-carbaldehyde of formula (XIV). Compound (XI) or (XIV) is reacted with benzoyl peroxide as radical initiator, and triethylsilane, to obtain (2R,5R)-4-(benzyloxy)-5-hydroxy-1',4'-dihydrospiro(oxane-2,2'-pyrrolo(2,1-c)(1,4)oxazine)-7'-carbaldehyde of formula (XII) or (2S,5R)-4-(benzyloxy)-5-hydroxy-1',4'-dihydrospiro(oxane-2,2'-pyrrolo(2,1-c)(1,4)oxazine)-7'-carbaldehyde of formula (XV). Compound (XII) or (XV) is subjected to benzyl removal reaction in presence of acid, to obtain rape pollen alkali A of formula (XVI) or caper alkali B of formula (XVII). Hydroxymethylation agent is p-formaldehyde or formalin solution. The deprotection of compound (IV) is carried out by reacting compound (IV) and protonic acid or Lewis acid in presence of methanol and/or ethanol at room temperature or in an ice bath, or reacting compound (IV) and 2,3-dichloro-5,6-dicyanobenzoquinone at 20-120 degrees C in presence of acetonitrile and water.