Crystal Structures of rac-Methyl- (3R*, 3aS*, 4R*, 7R*, 7aR*)-7-Acetoxymethyl)-3-benzyl-4,5-dimethyl-1-oxo-3a,4,7,7a-tetrahydroisoindoline-7a-carboxylate

The X-ray structures of the compounds 4 and 2 have been determined by direct methods and refined by least squares techniques. Crystals of C₂₂H₂₇NO₅ and C₂₇H₂₇NO₅ are triclinic, space groups Pī with lattice parameters a = 13.652 (5) Å, b = 10.926 (3) Å, c = 7.755 (2) Å, a = 111.554 (4) Å, β = 85.541 (3) Å, γ = 104.813 (4) Å, and a = 15.394 (4) Å, b = 9.674 (3) Å, c = 8.522 (3) Å, a = 111.04 (4) Å, ß = 93.65 (4) Å, γ = 95.01 (4) Å, respectively.     

Crystal and Molecular Structure of Tricarbonyl-[(1R*, 4S*, 4aS*, 9aR*)-1,4-epoxy-2, 3-dimethylidene-1,2,3,4,4a,9,9a,10-octahydroanthracene]iron

The thermal cyclodimerization of 5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene assisted by Fe₂ (CO)₉ gives the title complex 1 , a precursor for the synthesis of antitumoral anthracyclinones. The crystal structure of 1 has been determined by X-ray diffraction: a = 11.188 (1); c = 26.968 (3) Å; space group tetragonal, P4₁2₁2, Z = 8; R = 0.041; R_W = 0.033. The tricarbonyliron group is in the exo-position and the coordination polyhedron is tetragonal pyramidal. The NMR coupling constants are well-related to the observed dihedral angles between the non-aromatic protons and now give a reliable criterion for assigning the stereochemistry of the metal in d⁸-complexes of 2,3-dimethylidene-7-oxanorbornane derivatives.     

Combinatorial solution-phase synthesis of alkyl (1S*,2S*,3R*,5R*,6R*)-1-alkyl-3-aryl-6-benzoylamino-1-hydroxy-7- oxo-5-phenylhexahydropyrazolo[1,2-a]pyrazole-2-carboxylates

Combinatorial solution-phase cycloadditions of (1Z,4R*,5R*)-4-benzoylamino-5-phenylpyrazolidin-3-on-1-azomethine imines 3 to beta-keto esters 4 afforded a library of 26 bicyclic pyrazolidinones 5 in 6-89% yields and in 14-100% de. All products were isolated in >90% purity according to 1H NMR, and 25 of them were analytically pure. The structures of cycloadducts were confirmed by NMR and X-ray diffraction. Most of the products were isolated as mixtures of the major (1S*,2S*,3R*,5R*,6R*)-epimers 5 and the minor (1R*,2S*,3R*,5R*,6R*)-epimers 6. Epimerization of cycloadducts 5/6 at the anomeric position 1 in solution was confirmed by 1H NMR.     

New atropoisomeric alkenylphenylglycine derivatives: Synthesis of (5R*)- and (5S*)-isomers of (1R*,3aR*,4S*,11S*)-3a,5,9,11-tetramethyl-4,5-dihydro-3aH-1,4-methano[1,3]oxazolo[3,2-a]quinolin-2-one

We synthesized methyl ester of N-(1-methylbut-2-en-1-yl)-N-phenylglycine which underwent acid catalyzed aromatic amino Claisen rearrangement to provide methyl-N-[2-(1-methylbut-2-en-1-yl)phenyl]glycinate. A mixture of syn- and anti-atropisomeric methyl-N-acetyl-N-[4-methyl-2-(1-methylbut-2-en-1-yl)phenyl]glycinates was obtained either by the reaction of this ester with acetyl bromide or by the reaction of the sodium salt of N-acetyl-2-(1-methylbut-2-en-1-yl)-4-methylaniline with methyl bromoacetate. Upon saponification of the synthesized ester mixture the syn-atropisomer of N-acetyl-N-[4-methyl-2-(1-methylbut-2-en-1-yl)phenyl]glycine was isolated by fractional crystallization. Treatment of the obtained acids with acetic anhydride, ethyl chloroformate, dicyclohexylcarbodiimide or isopropenylacetate leads to compounds of 4,5-dihydro-3aH-methano[1,3]oxazolo[3,2-a]quinolin-2-one structure.     

(1S*,2S*,4S*,5S*)‐Cyclo­hexa­ne‐1,2,4,5‐tetrol monohydrate

In the title compound, C₆H₁₂O₄·H₂O, 1,4/2,5‐cyclo­hexane­tetrol and water mol­ecules are seen to possess twofold symmetry. All four hydrox­yl groups of the tetrol participate in extensive inter­molecular O—H⋯O hydrogen bonding to form mol­ecular tapes propagating along the a axis. Translationally related tapes along the c axis are held together by four coordinated water mol­ecules.