974
A. Srikrishna, G. Satyanarayana, and U. V. Desai
(1:50) as eluent furnished the ester 16 (240 mg, 84%) as oil. IR (neat): nmax
/
cm21 1732, 1163, 769. 1H NMR (300 MHz, CDCl3 þ CCl4): d 6.95 (3H, brs,
Ar-H), 5.72 (1H, ddt, J 17.1, 10.2, and 6.9 Hz, H-3), 5.05 (1H, d, J, 17.1 Hz)
and 5.01 (1H, d, J, 10.2 Hz) [H-4], 4.01 (2H, q, J, 7.2 Hz, OCH2CH3), 2.99
(1H, dd, J 14.1 and 7.2 Hz), 2.82 (1H, dd, J 14.1 and 7.2 Hz), 2.76–2.60
(1H, m), 2.58–2.45 (1H, m), 2.40–2.10 (1H, m), 2.32 (6H, s, 2 ꢀ ArCH3),
1.10 (3H, t, J 7.2 Hz, OCH2CH3). 13C NMR (75 MHz, CDCl3 þ CCl4): d
175.0 (C, OC55O), 136.6 (2 C, C, C-20 and 60), 135.9 (C, C-10), 135.5 (CH,
C-3), 128.4 (2 C, CH, C-30 and 50), 126.2 (CH, C-40), 117.0 (CH2, C-4),
60.1 (CH2, OCH2CH3), 45.1 (CH, C-2), 36.3 (CH2), 32.1 (CH2), 20.4 (2 C,
CH3), 14.2 (CH3, OCH2CH3). HRMS: m/z calcd. for C16H22O2Na
(M þ Na): 269.1517. Found: 269.1529.
3-(2,6-Dimethylbenzyl)-2-methylhex-5-en-2-ol (17)
To a cold (08C), magnetically stirred solution of methylmagnesium iodide
(9.1 mmol) [prepared from magnesium (218 mg, 9.1 mmol), methyl iodide
(0.66 ml, 10.58 mmol), and a catalytic amount of iodine in 3 ml of dry ether]
was added a solution of the ester 16 (186 mg, 0.76 mmol) in dry ether (2 ml).
The reaction mixture was slowly warmed up to rt and stirred for 5 h. It was
then poured into saturated aq. NH4Cl solution and extracted with ether
(3 ꢀ 3 ml). The ether extract was washed with brine and dried (Na2SO4). Evap-
oration of the solvent and purification of the residue on a silica-gel column
using ethyl acetate–hexane (1:10 to 1:5) as eluent furnished the tertiary
1
alcohol 17 (157 mg, 90%) as oil. IR (neat): nmax/cm21 3452, 767. H NMR
(300 MHz, CDCl3 þ CCl4): d 6.98 (3 H, brs, Ar-H), 5.72–5.52 (1H, m, H-5),
4.87 (1H, d, J 18.0 Hz) and 4.82 (1H, d, J 9.9 Hz) [H-6], 2.87 (1H, dd, J 13.5
and 4.2 Hz) and 2.58 (1H, dd, J 13.5 and 10.5 Hz) [ArCH2], 2.35 (6H, s,
2 ꢀ ArCH3), 2.25–2.15 (1H, m), 2.10–1.90 (2H, m), 1.70 (1H, s, OH), 1.32
(3H, s) and 1.29 (3H, s) [2 ꢀ tert-CH3]. 13C NMR (75 MHz, CDCl3 þ CCl4):
d 139.9 (CH, C-5), 137.7 (C, C-10), 136.6 (2 C, C, C-20 and 60), 128.4 (2 C,
CH, C-30 and 50), 125.9 (CH, C-40), 115.0 (CH2, C-6), 74.5 (C, C-2), 48.9
(CH, C-3), 34.1 (CH2), 30.3 (CH2), 27.9 (CH3) and 26.9 (CH3) [2 ꢀ tert-
CH3], 20.9 (2 C, CH3, 2 ꢀ ArCH3). HRMS: m/z calcd. for C16H24ONa
(M þ Na): 255.1725. Found: 255.1735.
4-(2,6-Dimethylbenzyl)-5,5-dimethyltetrahydrofuran-2-ol (18)
A precooled (2708C) mixture of ozone in oxygen was passed through a cold
(2708C) solution of the olefin 17 (70 mg, 0.30 mmol) and a catalytic amount
of NaHCO3 in methanol (2 ml) and CH2Cl2 (8 ml) for 1 min. The reaction
mixture was flushed off with oxygen, and dimethyl sulfide (0.11 ml,
1.51 mmol) was added to the reaction mixture. It was then slowly warmed