Heterocycles

Heterocycles

Vedejs, E. and Fields, S. "Reaction of Thioaldehydes with 5-Alkoxyoxazoles: A New Route to 3 Thiazolines", J. Org. Chem., 1988, 53, 4663.

Abstract:Generation of thioaldehydes RC(S)H (R = H, Me, PhCH2CH2, Ph, CO2Et), by photolysis of PhCOCH2SCH2R or by thermolysis of thiabicycloheptenes I, in the presence of oxazoles II (R1 = H, R2 = Me; R1 = Me, R2 = Ph) affords III, resp.  A mechanism involving an unstable Diels-Alder adduct IV is most likely.

Brewster, William K; Fields, Stephen C.; Lo, William C. and Lowe, Christian T. "Electrophilic Fluorination: The Aminopyridine Dilemma". Tetrahedron Lett. 2009, 51, 79.

Abstract: An unusually high yielding fluorination of aminopyralid using F-TEDA (SELECTFLOR) in warm water, followed by kinetic resoln. (via iterative esterification/sapon.) of the crude fluorination product with dry HCl in methanol produced pure ring-fluorinated pyridine in an overall yield of 31% for the two steps.

Balko, Terry William; Fields, Stephen Craig; Irvine, Nicholas Martin; Lowe, Christian Thomas; Schmitzer, Paul Richard From U.S. Pat. Appl. Publ. (2005), US 20050032651 A1 20050210. Language: English, Database: CAPLUS

Abstract:  6-(1,1-Difluoroalkyl)-4-aminopicolinate derivs. I (Y = 1,1-difluoroalkyl; W = NO2, N3, N:CR1R2 or NHN:CR3R4; R1,R2 = H, alkyl, alkenyl, alkynyl, aryl, heteroaryl, alkoxy, amino, acyl, etc.; R3, R4 = H, alkyl, alkenyl, alkynyl, aryl or heteroaryl; :CR3R4 = 5- or 6-membered satd. ring) are prepd. as broad-spectrum herbicides.

Fields, S. C.; Parker, M. H.; Erickson, W. R. "A Simple Route to Unsymmetrically Substituted 1,2,4,5-Tetrazines", J. Org.Chem., 1994, 59, 8284.

Abstract:  Heterocyclization of RC(OMe)3 (R = H, Me) or DMF di-Me acetal with [H2NNHC(SMe):N+HNH2]I- (I) followed by in situ oxidn. afforded tetrazines II [R = H (35%), Me (40%)]. Analogous cyclization of N,N-dimethylpivalamide Vilsmeier salt [Me3CCCl:N+Me2]Cl- with I, followed by in situ oxidn. and amination, afforded hindered tetrazine III (20-30% overall).

Erickson, W. R.; McKennon, M. J. "Unexpected Truce-Smiles Type Rearrangement of 2 (2' Pyridyloxy) phenylacetic Esters: Synthesis of 3 pyridyl-2-benzofuranones". Tetrahedron Lett., 2000, 41, 4541.

Abstract:  Enolization of (pyridyloxy)phenylacetic acid esters I (R, R1 = 6-F3C, H; 3-F3C, 5-Cl; H, H; 3-Cl, H) with either KH or NaH induced a Truce-Smiles rearrangement, producing the pyridinylbenzofuranones II. Rearrangement of a 2-(4-nitrophenoxy)phenylacetate and a 2-(2'-pyrimidyloxy)phenylacetate produced similar results. The benzofuranones II with a substituent at C-3 of the pyridine ring underwent enolization to the corresponding benzofuranols.

Sabol, M. R.; Owen, J. M.; Erickson, W. R. "A Novel and Efficient Synthesis of 2,3 Dichloroquinoline". Synth. Commun. 2000, 30, 427.

Abstract:  2,3-Dichloroquinoline was prepd. in 3 steps in good overall yield from com. 3-bromoquinoline via N-oxide formation and rearrangement to 3-bromocarbostyril, followed by a 1-pot conversion to 3-bromo-2-chloroquinoline and halogen exchange to the title compd.