Two reaction pathways and their diastereoselectivity-determining steps of the asymmetric desymmetrization of (R)-2-(α-methylbenzyl)amino-1,3-propanediol 1 with 2-chloroethyl chloroformate (CCF) and with N,N′-disuccinimidyl carbonate giving (4S,αR)-4-hydroxymethyl-3-α-methylbenzyl-2-oxazolidinones (4S)-3 and its (4R,αR)-diastereomer (4R)-3 were investigated. The reaction of serinol 1 and CCF to give the corresponding carbonates was not a diastereoselectivity-determining step. The carbonates gave (R)-5-(α-methylbenzyl)amino-1,3-dioxan-2-one 4 after addition of DBU, and an intramolecular acyl transfer of 4 was found to be a diastereoselectivity-determining step to give (4S)-3. Conversely, the reaction of serinol 1 and N,N′-disuccinimidyl carbonate afforded directly the opposite diastereomer (4R)-3 but not via the intermediate 4. Thus, their diastereoselectivities depended on the acylating reagent.

The photochemical C–C bond cleavage of bicyclic aziridines 7 and subsequent [3 + 2] cycloaddition with electron-deficient alkenes and alkynes afforded the novel head-to-head adducts selectively and efficiently. The adducts contain the naturally occurring 8-azabicyclo[3.2.1]octane skeleton (e.g. tropane alkaloids). The aziridine 8 fused with a 6-membered ring also afforded the cycloadducts but in poor yields. The methylaziridine 9 reacted with an electron-deficient alkene, affording the head-to-tail adduct 23 in addition to head-to-head adducts 22a and 22b. The photoreactions of bicyclic aziridines with alkenes and alkynes indicate a similar behavior to that of aziridines with a linear chain.

Both enantiomers of cytoxazone, (−)-1 and (+)-1, were synthesized using the Petasis reaction of dl-glyceraldehyde 2, 4-methoxyphenylboronic acid 3 and (R)-1-(1-naphthyl)ethylamine 7, following formation of an oxazolidin-2-one ring.(4R,5R)-5-Hydroxymethyl-4-(4-methoxyphenyl)-3-[(R)-1-(1-naphthyl)ethyl]oxazolidin-2-oneC23H24NO4Ee >98%[α]D30=-104.9 (c = 1.7, CHCl3)Source of chirality: (R)-1-(1-naphthyl)ethylamineAbsolute configuration: (4R,5R,1′R)(4S,5R)-5-Hydroxymethyl-4-(4-methoxyphenyl)-3-[(R)-1-(1-naphthyl)ethyl]oxazolidin-2-oneC23H24NO4Ee >98%[α]D30=+7.4 (c = 1.4, CHCl3)Source of chirality: (R)-1-(1-naphthyl)ethylamineAbsolute configuration: (4S,5S,1′R)

Mono-O-acylation of (R)-2-(α-methylbenzyl)amino-1,3-propanediol 1 with 4-nitrobenzoyl chloride and DMAP in dichloromethane at room temperature gave crystals of optically active (2S,αR)-3-hydroxy-2-(α-methylbenzyl)aminopropyl 4-nitrobenzoate hydrochloride [(2S)-2a·HCl] in 33% yield by fractional crystallization. Optically active oxazolidinones, aziridines, and serinol derivatives were synthesized from the benzoate (2S)-2a.Graphic(2S,αR)-3-Hydroxy-2-(α-methylbenzyl)aminopropyl 4-nitrobenzoate hydrochlorideC18H20N2O5·HClE.e. >98%[α]D21=−15.4 (c 1.0, DMSO)Source of chirality: (R)-(α-methylbenzyl)amineAbsolute configuration: (2S,αR)(2S,αR)-3-Hydroxy-2-(α-methylbenzyl)aminopropyl 4-nitrobenzoateC18H20N2O5E.e. >98%[α]D21=−14.4 (c 1.0, CHCl3)Source of chirality: (R)-(α-methylbenzyl)amineAbsolute configuration: (2S,αR)(2S,αR)-3-Hydroxy-2-(α-methylbenzyl)aminopropyl benzoate hydrochlorideC18H21NO3·HClE.e. >98%[α]D21=−12.1 (c 1.0, MeOH)Source of chirality: (R)-(α-methylbenzyl)amineAbsolute configuration: (2S,αR)(2S,αR)-3-Hydroxy-2-(α-methylbenzyl)aminopropyl benzoate hydrobromideC18H21NO3·HBrE.e. >98%[α]D21=−6.5 (c 1.0, MeOH)Source of chirality: (R)-(α-methylbenzyl)amineAbsolute configuration: (2S,αR)(2S,αR)-3-Hydroxy-2-(α-methylbenzyl)aminopropyl benzoateC18H21NO3E.e. >98%[α]D21=−11.3 (c 0.3, CHCl3)Source of chirality: (R)-(α-methylbenzyl)amineAbsolute configuration: (2S,αR)(2R,αR)-3-Hydroxy-2-(α-methylbenzyl)aminopropyl 4-nitrobenzoateC18H20N2O5E.e. >98%[α]D21=+46.6 (c 1.0, CHCl3)Source of chirality: (R)-(α-methylbenzyl)amineAbsolute configuration: (2R,αR)(αR)-2-(α-Methylbenzyl)amino-1,3-propyl di-4-nitrobenzoateC25H23N3O8E.e. >98%[α]D21=−3.2 (c 0.3, CHCl3)Source of chirality: (R)-(α-methylbenzyl)amineAbsolute configuration: (αR)(αR)-2-(α-Methylbenzyl)amino-1,3-propyl dibenzoateC25H25NO4E.e. >98%[α]D21=−18.6 (c 0.5, CHCl3)Source of chirality: (R)-(α-methylbenzyl)amineAbsolute configuration: (2S,αR)(4S,αR)-(3-α-Methylbenzyl-2-oxazolidinon-4-yl)methyl 4-nitrobenzoateC19H18N2O6E.e. >98%[α]D26=−51.5 (c 1.1, CHCl3).Source of chirality: (R)-(α-methylbenzyl)amineAbsolute configuration: (4S,αR)(4S,αR)-4-Hydroxymethyl-3-α-methylbenzyl-2-oxazolidinoneC12H15NO3E.e. >98%[α]D26=+102.1 (c 1.0, CHCl3)Source of chirality: (R)-(α-methylbenzyl)amineAbsolute configuration: (4S,αR)(2S,αR)-1-α-Methylbenzyl-2-aziridinyl)methyl 4-nitrobenzoateC18H18N2O4E.e. >98%[α]D28=+31.4 (c 1.1, CHCl3)Source of chirality: (R)-(α-methylbenzyl)amineAbsolute configuration: (2S,αR)(2R,αR)-3-(tert-Butyldimethylsilyl)oxy-2-(N-α-methylbenzyl)aminopropyl 4-nitrobenzoateC24H34N2O5SiE.e. >98%[α]D26=−0.8 (c 1.0, CHCl3)Source of chirality: (R)-(α-methylbenzyl)amineAbsolute configuration: (2R,αR)(2R,αR)-3-(tert-Butyldimethylsilyl)oxy-2-(N-α-methylbenzyl)amino-1-propanolC17H31NO2SiE.e. >98%[α]D26=−0.3 (c 0.46, CHCl3)Source of chirality: (R)-(α-methylbenzyl)amineAbsolute configuration: (2R,αR)

The photoreactions of α,β-unsaturated γ,δ-epoxy nitriles 1, 2, 13 and 16 with triethylamine give rise to novel 1 ∶ 1 α-adducts (e.g., 5) efficiently. After treatment with silica gel, the adducts undergo retro-Michael reaction leading to the corresponding α-alkylidenenitrile derivatives (e.g., 3). The epoxy nitrile 1 also reacts with various tertiary amines to afford α-adducts. The reaction of 1 and the silylamine 24 gives mainly methylene derivative 22 and silylated compound 25 after treatment with silica gel. The reaction may proceed via single- electron-transfer from the amine to the excited epoxy nitrile.

The photochemical C–C bond cleavage of bicyclic aziridines 7 and subsequent [3 + 2] cycloaddition with electron-deficient alkenes and alkynes afforded the novel head-to-head adducts selectively and efficiently. The adducts contain the naturally occurring 8-azabicyclo[3.2.1]octane skeleton (e.g. tropane alkaloids). The aziridine 8 fused with a 6-membered ring also afforded the cycloadducts but in poor yields. The methylaziridine 9 reacted with an electron-deficient alkene, affording the head-to-tail adduct 23 in addition to head-to-head adducts 22a and 22b. The photoreactions of bicyclic aziridines with alkenes and alkynes indicate a similar behavior to that of aziridines with a linear chain.