Preparation of Homobenzyl and Homoallyl Alcohols by the Hydroboration Method^1,2

Stereoselective Preparation and Reactions of Configurationally Defined Dialkylzinc Compounds

“…Starting materials: The following starting materials were prepared according to literature procedures: ethyl a-(bromomethyl)acrylate, [17] 1-phenylcyclopent-1-ene (5 b), [18] 1-methyl-3H-indene (5 c), [19] 3,4-dihydro-1-methylnaphthalene (5 d), [19] E-2-phenylbut-2-ene (E-9), [20] Z-2-phenylbut-2-ene (Z-9), [20] E-2-(2-p-anisyl)-but-2-ene (E-10), [21] Z-2-(2-p-anisyl)-but-2-ene (Z-10), [21] E-3-methyl-5-phenylpent-2-ene (E-12), [22] Z-3-methyl-5-phenylpent-2-ene (Z-12). [22] Preparation of the starting materials Diisopropylzinc: A 1.3m solution of isopropylmagnesium bromide in diethyl ether was prepared from 2-bromopropane (38.8 g, 0.32 mol) and magnesium (8.5 g, 0.35 mol) and transferred by cannula to a 500 mL 2-necked flask.…”

“…For the boron ± zinc exchange, the reaction mixture was stirred at 0 8C for 10 h; IR (film): n Ä 3062 (m), 3029 (m), 2956 (vs), 2871 (s), 1957 (s), 1603 (m), 1493 (m), 1453 (s), 843 (s), 754 (s), 700 (vs); 1 H NMR (CDCl 3 ,300 MHz): d 7.39 ± 7.26 (m,5 H),5.20 (q,J 6.6 Hz,1 H),4.78 ± 4.61 (m,2 H) d 207.9, 144.5, 128.2 (2C), 127.4 (2C), 125.9, 93.1, 75.5, 52.6, 46.54, 34.90, 32.58, 23.9; cis product: d 141.2, 128.7 (2C), 127.2 (2C), 127.1, 91.4, 74.9, 49.5, 43.3, 30.5, 29.1, 23 (20), 39 (19); elemental analysis (%) calcd for C 14 H 16 (184.28): C 91.25,H 8.75,found: C 91.41,cyclohexane (16 h 4, 131,4, 128.1, 127.9, 127.6, 127.3, 126.2, 124.0, 93.3, 81.7, 50.2, 37.0, 34.1, 33.6, 26.6, 26.3; cis product: d 145.0, 131.4, 128.1, 128.0, 127.8, 127.6, 127.3, 128.2, 91.0, 84.3, 46.9, 36.1, 32.5, 27.2, 26.6, 21.5 7, 131.5, 128.3, 128.1, 127.4, 127.2, 126.3, 124.1, 93.0, 81.5, 53.2, 39.5, 33.8, 33.7, 24 trans-1-Methyl-2-(2'-phenyl-1'-ethynyl)-2,3-dihydro-1H-indene (16 j): Reaction of 1-methyl-3H-ind-1-ene (5 c) and 1-bromo-2-phenylacetylene according to general procedure II afforded 16 j as a clear oil (0.976 g, 42 % yield) with a trans ± cis ratio of 93:7. For the boron ± zinc exchange, the reaction mixture was stirred at 0 8C for 10 h; IR ( 4,141.5,132.4 (2C),131.6,129.11,128.5,128.1 (2C),126.6,124.1,122.9,91.9,81.6,46.7,40.2,38.8,17.6;MS (EI): m/z (%): 232 (56) [M ], 231 (23), 218 (19), 217 (97), 216 (21), 215 (37), 130 (32), 115 (32); HRMS calcd. for C 18 H 16 : 232.1251, found: 232.1209.…”

“…After 6.5 h at room temperature, the boron ± zinc conversion was 48 %; IR ( 7,141.8,126.4,124.1,122.9,81.9,81.2,46.8,39.8,39.2,31.2,21.9,18.5,17.4,13.7;MS (EI): m/z (%): 213 (10) [M H], 212 (51) [M ], 170 (51), 169 (22), 165 (10), 156 (23), 155 (100), 154 (19), 153 (16), 152 (18), 143 (38), 142 (35), 141 (83), 130 (55), 129 (53), 128 (21), 117 (13), 115 (26), 91 (16), 55 (12); HRMS calcd for C 16 H 20 : 212.1565, found: 212.1565.…”

A simple and inexpensive procedure for low valent copper mediated benzylation of aldehydes in wet medium: synthesis of protease inhibitor synthon

“…In addition, some other strategies were reported in earlier days to prepare homobenzylic alcohols involving hydroboration of 1-aryl-alkenes, 3 We present here a very simple and practically viable procedure for benzylation of aldehydes in wet solvent. Our strategy was based on judicious application of bimetal redox strategy (Scheme 1) 9 to effect this reaction in wet condition.…”

Trimethylenemethane Derivatives Stabilized by Conjugation II − Concerted or Nonconcerted Generation?

“…Ϫ MS (70 eV); m/z (%): 148(14) [M ϩ ], 133 (84), 115(15), 105 (100), 91 (56), 77(28), 65(22), 51(19), 41 (53). 139.3.…”