6-(4-Fluorophenyl)-8-phenyl-2,3-dihydro-4H-imidazo[5,1-b][1,3]thiazin-4-one: an unusual [6-5] fused-ring system.

The title compound, C(18)H(13)FN(2)OS, is the first structural example of a [6-5] fused ring incorporating the 2,3-dihydro-4H-imidazo[5,1-b][1,3]thiazin-4-one molecular scaffold. The six-membered 2,3-dihydro-1,3-thiazin-4-one ring adopts an envelope conformation, with the S-CH(2) C atom displaced by 0.761 (2) A from the five-atom plane (all within 0.

Solution-phase synthesis of a tricyclic pyrrole-2-carboxamide discovery library applying a stetter-Paal-Knorr reaction sequence.

The solution-phase synthesis of a discovery library of 178 tricyclic pyrrole-2-carboxamides was accomplished in nine steps and seven purifications starting with three benzoyl-protected amino acid methyl esters. Further diversity was introduced by two glyoxaldehydes and 41 primary amines. The combination of Pauson-Khand, Stetter, and microwave-assisted Paal-Knorr reactions was applied as a key sequence.

Microwave-assisted "libraries from libraries" approach toward the synthesis of allyl- and C-cyclopropylalkylamides.

Cascade reactions of internal and terminal alkynes, zirconocene hydrochloride, dimethylzinc, and phosphinoyl imines (prepared in one step from aldehydes and diphenylphosphinoyl amide) lead to allylic phosphinoyl amides after aqueous workup. Microwave acceleration allows the completion of this one-pot reaction sequence in 10 min. These allylic amides can be converted into a variety of derivatives, including carbamates and sulfonamides, or reacted prior to workup with diiodomethane to give novel C-cyclopropylalkylamides.

Indole synthesis by controlled carbolithiation of o-aminostyrenes.

An effective synthesis of the functionalized indole ring system has been developed from substituted o-aminostyrene starting material. Our methodology involves a novel cascade reaction sequence of alkyllithium addition to the styrene double bond and subsequent trapping of the intermediate organolithium with a suitable electrophile, followed by an in situ ring closure and dehydration to generate the indole ring. This new reaction sequence allows for the introduction of molecular diversity at all positions on the indole scaffold.

tert-Butyl 5-methoxy-3-pentylindole-1-carboxylate.

The molecule of the title compound, C(19)H(27)NO(3), is essentially planar, with all non-H atoms within 0.2 A of the nine-membered indole plane, except for the three tert-butyl C atoms. The C(5) pentyl chain is in an extended conformation, with three torsion angles of 179.

New organolithium addition methodology to diversely functionalized indoles.

A novel synthetic approach to diversely functionalized indoles is described. Boc-protected ortho-aminostyrenes undergo an alkyllithium addition reaction, thereby generating a lithiated intermediate, which upon reaction with specific electrophiles sets up a cascade reaction process between the reacted electrophile and ortho-amino substituent, facilitating an in situ ring closure, followed by dehydration, to generate an indole ring system. This methodology is demonstrated by the synthesis of a range of 3,5-, 1,3,5-, and 2,3,5-substituted indoles.

Microwave parallel library generation: comparison of a conventional- and microwave-generated substituted 4(5)-sulfanyl-1H-imidazole library.

A methodology for the microwave parallel synthesis of libraries is described. The procedure involves the use of an array of expandable reaction vessels, which can accommodate pressure buildup within the vessel due to heating without loss of volatile solvents or reagents. A demonstration 24-membered library of substituted 4(5)-sulfanyl-1H-imidazoles was generated by both conventional and microwave procedures, achieving a reduction from 12 h to 16 min in library generation time for the microwave approach.