R. A. Olofson

A regiospecific and stereospecific route to enol carbonates and carbamates: closer look at a “naked anion”

Abstract A fluoride ion catalyzed reaction which affords the title compounds in good yield from enol silyl ethers is described.

A simple synthesis of 1-(1,3-butadienyl) carbonates and carbamates

Crotonaldehyde and its congeners are conveniently and often stereospecifically converted to trans-1-(1,3-butadienyl) carbonates and carbamates by treatment first with potassium tert-butoxide and then with a chloroformate or carbamyl chloride.

O-1-(1,3-butadienyl) carbamates as diels-alder dienes: Stereospecific synthesis of (±)-Hernandulcin and congeners

Abstract The TiCl 4 -catalyzed addition of the title reactants to vinyl ketones regio- and stereospecifically yields cis -disubs, cyclohexenes which add RMgX stereospecifically to the ketone. A final product in this sequence is the intensely sweet sesquiterpene, hernandulcin.

Poly(vinyl chloroformate) and its derivatives: 5. New poly(vinyl carbamates) and poly(vinyl thiocarbonates)

Abstract New poly(vinyl carbamates) and poly(vinyl thiocarbonates) have been prepared either by free radical polymerization of monomers or by chemical modification of poly(vinyl chloroformate) with appropriate amines and thiols using phase transfer catalysis. The structure of these polymers has been examined by i.r. and 13 C n.m.r. spectroscopy and their thermal behaviour has been studied.

1,3,4,6-Tetramethyl-1,4-dihydro-1,2,4,5-tetrazine, C_6H_(12)N_4

M_r =140∙19, monoclinic, P2_1/n, a = 10∙612(3), b=6∙820(1), c= 10∙975 (2) A, β=95∙31(2)°, V=790.9(5) A^3, Z=4, D_m=1.13(5) (flotation), D_x = 1∙177 g cm^(-3), Mo Kα, λ = 0.71073 A, μ= 0.848 cm^(-1), F(000) = 304, T= 295 K, R = 0∙077 for 704 observed reflections. This potentially antiaromatic or homoaromatic ring system has a flattened boat conformation with both N-methyls in equatorial positions. Bond angles and distances (excluding Hs) predicted to be symmetry equivalent exhibit variations of 0.002-0.014 A and 0.0-2.0°. Substantial delocalization of the electron lone pairs of N(1) and N(4) is found.

A novel benzo[]quinolizidine rearrangement involving intramolecular carbamyl-chloride-induced cleavage of a tertiary amine

Abstract The free base of benzoquinolizidine 3 undergoes a facile rearrangement to pyrimidoisoquinoline 4 , the structure of which was confirmed by x-ray crystallography.The regiospecificity of this novel rearrangement is governed by stereoelectronic factors.

Synthesis, structure, and chemistry of a 1-thia-4-azanaphthalene

Abstract From a crystal structure determination and thermal rearrangement studies, it is evident that 1-methyl-2-carbethoxy-3-phenyl-1-thia-4-azanaphthalene is an alias for a molecule more properly represented by a name emphasizing its zwitterionic character.

Base-induced fragmentations of 1,2,4-oxadiazolin-5-ones and their N-alkyl salts

Abstract Titration with triethylamine suffices to cleave the previously unknown title compounds ( 2 and 3 ) to cyanamides and carbodiimides, respectively.