An efficient stereocontroued synthesis of (–)-detoxinine

A Stereoselective and Short Total Synthesis of the Polyhydroxylated γ‐Amino Acid (−)‐Detoxinine, Based on Stereoselective Preparation of Dihydropyrrole Derivatives from Lithiated Alkoxyallenes

“…We mentioned above that the next hurdle in our route might be the selective oxidation of the primary hydroxy group. We tried several methods—including variants which first provide an intermediate aldehyde20, 7 to be further oxidized into the carboxylic acid—but finally found that direct oxidation of 29 with platinum dioxide and oxygen provided the most satisfactory result 21, 15c. The generated carboxylic acid immediately cyclized to δ ‐lactone 30 , isolated in 66 % yield.…”

“…M.p. 140–141 °C (literature value:15c 141–142 °C); [ α ]$\rm{_{D}^{20}}$ =−35.9 ( c =0.73; CHCl 3 ) (literature value: −6.5 ( c =1.0, CHCl 3 ),15b −31.7 (CHCl 3 )15c); 1 H NMR (500 MHz, C 6 D 6 , 334 K): δ =5.12 (s, 1 H; OH), 3.74–3.67 (m, 2 H; 3 a‐H, 6‐H), 3.38 (t, J =5.0 Hz, 1 H; 7 a‐H), 3.08–3.03 (m, 1 H; 2‐H A ), 2.91 (dt, J =6.1, 11.3 Hz, 1 H; 2‐H B ), 2.72 (dd, J =4.2, 15.0 Hz, 1 H; 6‐H A ), 2.12 (dd, J =12.7, 15.0 Hz, 1 H; 6‐H B ), 1.51–1.45 (m, 1 H; 3‐H A ), 1.37 (s, 9 H; C(CH 3 ) 3 ), 0.97 ppm (dddd, J =5.1, 8.9, 11.3, 13.9 Hz, 1 H; 3‐H B ); 13 C NMR (125.8 MHz, CDCl 3 ): δ =169.6 (s; C‐5), 156.0 (s; C(O)OC(CH 3 ) 3 ), 80.6 (s; C (CH 3 ) 3 ), 78.0 (d; C‐3 a), 70.4 (d; C‐7), 66.2 (d; C‐7 a), 44.6 (t; C‐2), 36.3 (t; C‐6), 30.5 (t; C‐3), 28.3 ppm (q; C( C H 3 ) 3 ); IR (KBr): $\tilde \nu$ =3375 (OH), 3000–2885 (CH), 1715, 1695 cm −1 (CO); MS (80 eV, EI): m / z (%): 257 (1) [ M ] + , 242 (1) [ M −CH 3 ] + , 57 (100) [C(CH 3 ) 3 ] + ; HRMS (80 eV): C 12 H 19 NO 5 calcd 257.12632; found 257.12732; elemental analysis calcd (%) for C 12 H 19 NO 5 (257.1): C 55.73, H 7.25, N 5.15; found: C 56.02, H 7.44, N 5.44.…”

α,β‐Unsaturated γ‐Peptide Foldamers

“…Nevertheless, the E / Z selectivity has also been found to depend on the substituents bonded to the phosphorus atom. As demonstrated by Hensel and Fuchs [33] with N‐ benzyl‐ N ‐tosyl phenylalaninal and by Kogen and Nishi [34] with Cbz‐protected α‐aminoaldehydes, a shift of selectivity can be obtained with highly electrophilic β‐trifluoroethyl phosphonate.…”

Mechanism of the directing influence of functional groups and the geometry of reactant molecules on peroxide epoxidation of alkenes

“…The syn-directing effect is manifested in epoxidation of not only alkenols but also unsaturated carboxylic acids, 86,87 amides, 88,89 urethanes, urea derivatives, 6,90 acetals, sulfones, sulfoxides, 6 sulfamides 91 and ketones of the aliphatic and aromatic series. 92 In some cases, concerted or competing action of two groups has been observed.…”

“…92 In some cases, concerted or competing action of two groups has been observed. 6,89,90 Several variants have been considered for the mechanism of the directing influence of some groups, for example, those involving the formation of structures 92, 89 93 90 and 94 ± 96. 6 Kocovsky and Stary, 6 who studied a broad range of unsaturated (allylic and homoallylic) carbamates, amides, urethanes and esters, in particular, cyclohexene (97,98) and cyclopentene (99) derivatives and steroid type compounds 100 ± 105, including those differing in the position of the double bond, concluded that the stereodirecting influence exerted by the functional groups present in these substrates is due to involvement of the carbonyl oxygen atom, which carries the highest electron density into the hydrogen bond (see structure 95).…”