M. Parvez

Delnuttaline, (6β,9β,13β)-13-acetoxy-6,9-dihydroxyhetisan-2-one

The crystal structure of the C-20 diterpenoid alkaloid 6,9-dihydroxy-2-oxohetisan-13-yl acetate consists of two independent molecules in the asymmetric unit with average bond distances C(sp 3 )-C(sp 3 ) 1.55 (1), C(sp 3 )-C(sp 2 ) 1.52 (1), C=C 1.31 (1), N-C 1.51 (1), C(sp 3 )-O 1.46 (1), C(sp 2 )-O 1.35 (1) and C=0 1.22 (1) A. The structure is stabilized through a network of hydrogen bonds involving nitrogen and hydroxy groups with O...O and O...N separations in the range 2.688 (7)-2.903 (8) A

14-O-Benzoyl-8-ethoxybikhaconine and 14-O-Benzoyl-8-methoxybikhaconine

The molecular structures of two new C 19 norditerpenoid alkaloids, 14-O-benzoyl-8-methoxybikhaconine [(1α,6α,14α,16β)-20-ethyl- 13-hydroxy-1,6,8,16-tetramethoxy-4-methoxymethylaconitan-14-yl benzoate, C 33 H 47 NO 8 , (1)] and 14-O-benzoyl-8-ethoxybikhaconine [(1α,6α,14α,16β)-8-ethoxy-20-ethyl-13-hydroxy-1,6,16-trimethoxy-4-methoxymethylaconitan-14-yl benzoate, C 34 H 49 NO 8 , (2)], isolated for the first time from the roots of Aconitum chasmanthum Stapf ex Holmes of Pakistani origin, have been determined. The two alkaloids differ by one CH 2 moiety in a side chain (8-methoxy versus 8-ethoxy), co-crystallize in a 65 (2):35 (2) ratio, i.e. 0.65C 33 H 47 NO 8 .0.35C 34 H 49 NO 8 , and are inseparable by thin-layer and column chromatography. The conformations of the rings in the two alkaloids are: A and E, chairs; D, half-chair; C and F, envelopes; and B, boat. The molecular dimensions are normal; the mean bond distances are C sp 3-N 1.463(6), C sp 3-C sp 3 1.54(2), C sp 3-O 1.41(2), C sp 2-O 1.342(3) and C=O 1.204(4)A. There is a short intramolecular hydrogen bond with O…O and H…O distances of 2.556 (3) and 2.01 A, respectively.

10,16-Dioxatetracyclo[7.6.1.01,11.04,9]hexadecan-11-ol

The crystal structure of the title compound, C 14 H 22 O 3 , consists of independent molecules in each of which three six-membered rings and a five-membered ring are fused together. All the six-membered rings display chair conformations, while the five-membered ring has an envelope conformation. The molecular dimensions are normal with mean bond distances C sp 3-C sp 3 1.523 (10) and C sp 3-O 1.44 (2) A. Pairs of molecules lying about inversion centers are linked by O-H...O hydrogen bonds [O...O 2.806 (3) A].

[3aR-(3aα,4α,7α,7aα)]-2-Acetyl-4,8,8-trimethylperhydro-4,7-methano-1,2-benzisoselenazol-3a-ol

Crystals of the title compound, C 13 H 21 NO 2 Se, are composed of independent molecules wherein the six-membered ring of the camphor-derived moiety is fused with a novel five-membered heterocyclic ring incorporating Se and N atoms. The bond lengths and angles are normal, with Se-N and Se-C distances of 1.865(3) and 1.943 (3) A, respectively, and an N-Se-C angle of 87.1(2)°. The mean value of the C sp 3-C sp 3 bond length in the camphor moiety is 1.542(15)A. The five-membered ring has an N-envelope conformation and the molecules are hydrogen bonded forming chains extended along the b-axis direction, with Q...O and O-H...O separations of 2.769 (4) and 1.84 A, respectively.

Indaconitine 0.5-acetonitrile solvate

The crystal structure of indaconitine hemiacetonitrile solvate, [1α,6α,14α(E),16β]-20-ethyl-1,6,16-trimethoxy-4-methoxymethyl-3,13-dihydroxyaconitane-8,14-diyl 8-acetate 14-benzoate hemiacetonitrile solvate, C 34 H 47 NO 10 .0.5C 2 H 3 N, a C 19 norditerpenoid alkaloid isolated from the roots of Aconitum chasmanthum Stapf ex Holmes of Pakistani origin, contains a molecule of the alkaloid and half a molecule of the solvate in an asymmetric unit. The molecular dimensions are as expected. The fused ring system contains one boat, one half-chair, two chair and two envelope conformations. The crystal structure is stabilized by an intermolecular hydrogen bond between indaconitine and acetonitrile, with an O…N distance of 3.036 (6) A. An hydroxyl group is also involved in an intramolecular interaction with a methoxy group, with an O…O separation of 2.643 (5) A.

7-Oxaspiro[5.9]pentadecane-1,8,13-trione

The crystal structure of the title compound, C 14 H 20 O 4 , a macrocyclic lactone, is composed of independent molecules with normal molecular dimensions. The average bond distances are C sp 3-C sp3 1.526(6), C sp 3-C sp 2 1.514(14) and C=O 1.210(3)A. The six-membered ring adopts a chair conformation, while the ten-membered heterocyclic ring is in a boat-chair-boat (bcb) conformation. There are no unusual interactions between the molecules which are separated by normal van der Waals distances.

Chasmaconitine 0.5-Methanol Solvate

The crystal structure of chasmaconitine methanol solvate, C34H47NO9.0.5CH4O, a C19 diterpenoid alkaloid isolated from the roots of Aconitum chasmanthum Stapf ex Holmes of Pakistani origin contains discrete molecules separated by normal van der Waals distances. The fused ring system contains one boat, one half-chair, two envelope and two chair conformations. The molecular dimensions are normal with no interactions between the alkaloid and the disordered solvate molecules; the mean bond distances are Csp3—N 1.467 (14), Csp3—Csp3 1.54 (2), Csp3—O 1.42 (2), Csp2—O 1.337 (5) and C=O 1.197 (5) A.

3α-Bikhaconine Acetone Solvate

The crystal structure of 3α-bikhaconine acetone solvate [1a,6α,16β-trimethoxy-4β-(methoxymethyl)aconitane-3α,8β,13β,14α-tetrol acetone solvate, [C 25 H 41 NO 8 .C 3 H 6 O], a C 19 norditerpenoid alkaloid which has been partially synthesized from indaconitine, contains discrete molecules separated by normal van der Waals distances. The molecular dimensions are normal; the mean bond distances are C sp 3-N 1.471(9), C sp 3-C sp 3 1.54 (2) and C sp 3-O 1.425 (14) A. The fused-ring system contains two chair, one half-chair, two envelope and one boat conformation. There are both inter- and intramolecular hydrogen bonds, with O...O separations in the range 2.655(3)-3.048 (3) A and H...O interactions in the range 1.92-2.38 A. There are no interactions between the alkaloid and the solvate molecules.

Naphtho[2,3-b]cholestane

The crystal structure of the title compound, naphtho[2,3-b]cholestane, C 35 H 50 , is composed of independent molecules with normal molecular dimensions and no unusual contacts shorter than van der Waals distances.

Absolute Configuration of (S,S)-1,2-Dihydro-1,2-trans-acenaphthylenedicarboxylic Acid

The naphthalene ring system in the title compound, C 14 H 10 O 4 , is essentially planar and the fused cyclopentane ring is in a slightly twisted conformation. The carboxylic acid groups associate via intermolecular hydrogen bonds [O...O 2.610 (4) and 2.655 (3) A] forming chain structures that are held together by weak van der Waals interactions