Michael-type Reactions with α,α,ι,ι-Tetranitroalkanes¹

Addition reactions of alkenes with electronegatively substituted alcohols in the presence of xenon difluoride

“…The great variety of regioand stereo-isomers of substituted norbornanes attests to the complexity of the norbornyl system in the course of electrophilic reactions involving norbornyl cations. 8 This complexity may include hydride migrations and σ-bond shifts starting with intermediate 4, which lead to 2,5-disubstituted (8,9,16,17) and 2,7-disubstituted (7,11,18) norbornanes as well as nortricyclenes (5,12). Structure 13 is formed by direct addition of alcohol to 3.…”

“…(Conventional base-catalysed Michael additions of polynitroaliphatic alcohols to alkenes are unfeasible because of their alkaline deformylation cited above; they tend to give Michael adducts of the corresponding 1,1-dinitroalkanes. 18 ) In contrast, Table 3 shows examples of additions of polynitroaliphatic alcohols with efficiencies >80%: FDNE (1f) 90% and TNE (1g) 83%.…”

Nuclear bromination of thiopyrans and pyrans by N-bromosuccinimide

“…The reaction sohtion was stirred for 5 hr at room temperature and was slowly poured into 500 ml of anhydrous ether and stirred magnetically for 10 rnin to yield 3.56 g (94%) of 2-carbobenzyloxy-~-cycloserine hydrobromide after filtration and drying in vacuo: mp 128-131" dec; ir (KBr) 2800 (-IL",+Br), 1770 (C=O), 1760 cm-l (C=O); nmr (DXSO-d6) 6 iv-Carbobenzyloxy-D-alanyl-2-carbobenzyloxy-D-cycloserine (6).-A solution of 3.35 g (15 mmol) of N-carbobenzyloxy-D-alanine13 and 1.65 ml (15 mmol) of A'-methylmorpholine in 75 ml of tetrahydrofuran (dried over CaHz) in a 200 ml round-bottomed flask equipped with a thermometer and magnetic stirrer, and cooled in a Dry Ice-acetone bath, was treated with 15 mmol of isobutyl chloroformate. The reaction sohtion was stirred for 5 hr at room temperature and was slowly poured into 500 ml of anhydrous ether and stirred magnetically for 10 rnin to yield 3.56 g (94%) of 2-carbobenzyloxy-~-cycloserine hydrobromide after filtration and drying in vacuo: mp 128-131" dec; ir (KBr) 2800 (-IL",+Br), 1770 (C=O), 1760 cm-l (C=O); nmr (DXSO-d6) 6 iv-Carbobenzyloxy-D-alanyl-2-carbobenzyloxy-D-cycloserine (6).-A solution of 3.35 g (15 mmol) of N-carbobenzyloxy-D-alanine13 and 1.65 ml (15 mmol) of A'-methylmorpholine in 75 ml of tetrahydrofuran (dried over CaHz) in a 200 ml round-bottomed flask equipped with a thermometer and magnetic stirrer, and cooled in a Dry Ice-acetone bath, was treated with 15 mmol of isobutyl chloroformate.…”

“…Anal. Caled for CnHlaN204Br (316): C, 41.65; , 4.10; N, 8.33. Found: C, 40.71; , 4.16; N, 8.74. A7-Carbobenzyloxy-D-alanyl-2-carbobenzyloxy-D-cycloserine (6).-A solution of 3.35 g (15 mmol) of Ar-carbobenzyloxy-D-alanine13 and 1.65 ml (15 mmol) of Ar-methylmorpholine in 75 ml of tetrahydrofuran (dried over CaH2) in a 200 ml round-bottomed flask equipped with a thermometer and magnetic stirrer, and cooled in a Dry Ice-acetone bath, was treated with 15 mmol of isobutyl chloroformate. After stirring for 30 sec, a cold solution of 4.74 g (15 mmol) of 2-carbobenzyloxy-D-cycloserine hydrobromide and 1.65 ml (15 mmol) of A'-methylmorpholine in 35 ml of tetrahydrofuran was added.…”

“…Recrystallization from absolute ethanol afforded 4.33 g (65%) of (13) Prepared in 71% yield, mp 86-87°, [cí]26d +15.6°, by the procedure of M. Bergmann and L. Zervas, Ber., 66, 1192 (1932). 6: mp 149-151°; ir (KBr) 3310, 3280 (NH), 1770 (C=0), 1695. (C=0), 1665 cm-1 (C=0); Anal.…”