Four novel spirooxazacamphorsultam derivatives.

The chiral compounds (6aS,9S,10aR)-11,11-dimethyl-5,5-dioxo-2,3,8,9-tetrahydro-6H-6a,9-methanooxazaolo[2,3-i][2,1]benzisothiazol-10(7H)-one, C(12)H(17)NO(4)S, (1), (7aS,10S,11aR)-12,12-dimethyl-6,6-dioxo-3,4,9,10-tetrahydro-7H-7a,10-methano-2H-1,3-oxazino[2,3-i][2,1]benzisothiazol-11(8H)-one, C(13)H(19)NO(4)S, (2), (6aS,9S,10R,10aR)-11,11-dimethyl-5,5-dioxo-2,3,7,8,9,10-hexahydro-6H-6a,9-methanooxazolo[2,3-i][2,1]benzisothiazol-10-ol, C(12)H(19)NO(4)S, (3), and (7aS,10S,11R,11aR)-12,12-dimethyl-6,6-dioxo-3,4,8,9,10,11-hexahydro-7H-7a-methano-2H-[1,3]oxazino[2,3-i][2,1]benzisothiazol-11-ol, C(13)H(21)NO(4)S, (4), consist of a camphor core with a five-membered spirosultaoxazolidine or six-membered spirosultaoxazine, as both their keto and hydroxy derivatives. In each structure, the molecules are linked via hydrogen bonding to the sulfonyl O atoms, forming chains in the unit-cell b-axis direction. The chains interconnect via weak C-H.

Conjugate addition/Ireland-Claisen rearrangements of allyl fumarates: simple access to terminally differentiated succinates.

The conjugate addition of dialkylzinc reagents to allyl fumarates with subsequent Ireland-Claisen rearrangement has been accomplished yielding substituted unsymmetrical succinic acid derivatives. This one-pot reaction creates two new carbon-carbon bonds at contiguous stereogenic centers. The reaction proceeds for several alkylzinc reagents and substituted allyl fumarates.

Mechanism and scope of the cyanide-catalyzed cross silyl benzoin reaction.

In this work, cross silyl benzoin addition reactions between acylsilanes (1) and aldehydes (2) catalyzed by metal cyanides are described. Unsymmetrical aryl-, heteroaryl-, and alkyl-substituted benzoin adducts can be generated in moderate to excellent yields with complete regiocontrol using potassium cyanide and a phase transfer catalyst. From a screen of transition metal cyanide complexes, lanthanum tricyanide was identified as an improved second-generation catalyst for the cross silyl benzoin reaction.

Cross silyl benzoin additions catalyzed by lanthanum tricyanide.

From a screen of (cyanide)metal complexes, an improved catalyst for the cross silyl benzoin addition was discovered. Several M(CN)(3) complexes (M = Ce, Er, Sm, Y, Yb, La) were evaluated and lanthanum tricyanide was identified as the optimal catalyst. The catalyst, prepared in situ from LaCl(3), effects the selective coupling of aryl and alkyl acylsilanes with aryl, heteroaryl, alpha,beta-unsaturated, and aliphatic aldehydes.