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Showing posts with label 3-dioxane. Show all posts
Showing posts with label 3-dioxane. Show all posts

Tuesday 26 May 2015

2-(2,5-dimethoxyphenyl)-1,3-dioxane



   Reaction Scheme: <IMG src="/images/empty.gif"><IMG src="/images/empty.gif">Protection of benzaldehydes as cyclic acetals<IMG src="/images/empty.gif"><IMG src="/images/empty.gif">

Procedure

To 2,5-dimethoxybenzaldehyde (1.0 g, 6.02 mmol) in 1,3-propanediol (1.75 mL, 24.2 mmol, 4 eq.) were added (MeO)3CH (0.75 mL, 6.86 mmol, 1.1 eq.) andBu4N.Br3 (26 mg, 0.05 mmol, 0.01 eq.). After stirring at room temperature for 45 min the reaction was quenched with saturated NaHCO3 (5 mL) and H2O (20 mL). The mixture was then extracted with EtOAc (3 × 10 mL) and the combined organic fractions washed sequentially with 10% NaHCO3 (20 mL), H2O (4 × 20 mL) then dried (MgSO4) and concentrated in vacuo to give 2-(2,5-dimethoxyphenyl)-1,3-dioxane (1.35 g, 100%) as a colourless oil suitable for further use.
2-(2,5-dimethoxyphenyl)-1,3-dioxane:
1H NMR (500 MHz, CDCl3): δ = 1.41-1.45 (m, 1H), 2.21-2.28 (m, 1H), 3.79 (s, 3H), 3.80 (s, 3H), 3.98-4.04 (m, 2H), 4.24-4.27 (m, 2H), 5.85 (s, 1H), 6.81 (d, J = 8.9 Hz, 1H), 6.85 (dd, J = 8.9 and 3.1 Hz, 1H), 7.20 (d, J = 3.1 Hz, 1H).
13C NMR (125 MHz, CDCl3): δ = 25.9, 55.8, 56.4, 67.6, 96.8, 111.9, 112.3, 115.9, 127.7, 150.6, 153.9.
2-(3,4-dimethoxyphenyl)-1,3-dioxane:
1H NMR (500 MHz, CDCl3): δ = 1.43-1.46 (m, 1H), 2.19-2.27 (m, 1H), 3.87 (s, 3H), 3.91 (s, 3H), 3.96-4.01 (m, 2H), 4.25-4.28 (m, 2H), 5.46 (s, 1H), 6.85 (d, J = 8.0 Hz, 1H), 7.01 (dd, J = 8.0 and 2.0 Hz, 1H), 7.05 (d, J = 2.0 Hz, 1H).

Gopinath, R.; Haque, S. J.; Patel, B. K. J. Org. Chem., 2002, 67, 5842-5845. DOI: 10.1021/jo025701o



Abstract Image
Acyclic and cyclic acetals of various carbonyl compounds were obtained in excellent yields under a mild reaction condition in the presence of trialkyl orthoformate and a catalytic amount of tetrabutylammonium tribromide (TBATB) in absolute alcohol. Chemoselective acetalization of an aldehyde in the presence of ketone, unsymmetrical acetal formation, shorter reaction times, mild reaction conditions, the stability of acid-sensitive protecting groups, high efficiencies, facile isolation of the desired products, and the catalytic nature of the reagent make the present methodology a practical alternative.
 http://pubs.acs.org/doi/abs/10.1021/jo025701o



Figure
Scheme 1.  Proposed Mechanism of Acetalization

Other References

1. Wuts P. G. M.; Greene, T. W. "Greene's protective groups in organic synthesis", 4th Edition, 2007, John Wiley & Sons, Inc.
2. Donner, C. D. Synthesis, 2010, 415-420. DOI: 10.1055/s-0029-1217118
3. Tan, N. P. H.; Donner, C. D. Tetrahedron Lett., 2008, 49, 4160-4162. DOI: 10.1016/j.tetlet.2008.04.112




A TOUR


 JUNNAR, MAHARASHTRA INDIA
http://en.wikipedia.org/wiki/Junnar



 Map of junnar maharashtra


Junnar
जुन्नर
city
Junnar is located in Maharashtra
Junnar
Junnar
Location in Maharashtra, India
Coordinates: 19.2°N 73.88°ECoordinates: 19.2°N 73.88°E
Country  India
State Maharashtra
District Pune
Elevation 689 m (2,260 ft)
Population (2001)
 • Total 24,456
Languages
 • Official Marathi
Time zone IST (UTC+5:30)
Website [1]

 .
Lenyadri Caves

 
 Naneghat caves near Junnar

Shivneri fort

 

 
 

 

 
Photos JunnarOtur

 







 




Kukdeshwar temple at Pur- Junnar, Dist. Pune. Small shrine in the vicinity



 

Richly stone carved Buddhist caves on mountain at Lenyadri ; Ganesh Gufa ; Ashtavinayak ; Taluka


Photos JunnarGanesh Gate
GANESH GATE

Sunday 14 September 2014

(R)-2,5,5-Trimethyl-2-(oxiran-2-ylmethyl)-1,3-dioxane

Inline image 1

(R)-2,5,5-Trimethyl-2-(oxiran-2-ylmethyl)-1,3-dioxane

Rf 0.24 (PE: Et2O 5:1);

[α]D25 +8.5 (c 0.43, CHCl3);

 IR (neat, cm-1): 3052, 2955, 2984, 2869, 1474, 1412, 1377, 1363, 1349, 1309, 1244, 1211, 1191, 1168, 1121, 1041, 1023, 951, 908, 837, 798, 759, 679;

1H NMR (400 MHz, CDCl3):
δ = 3.28 (2H, d, J = 11.9; H6a, 7a),
3.14 (2H, d, J = 11.9; H6b,7b),
2.78 (1H, dddd, J = 6.3, 5.1, 4.3, 2.7; H2),
2.43 (1H, dd, J = 5.2, 4.3; H1a),
2.15 (1H, dd, J = 5.2, 2.7; H1b),
1.62 (1H, dd, J = 14.3, 5.1; H3a),
1.57 (1H, dd, J = 14.3, 6.3; H3b),
1.15 (3H, s; H5), 0.74 (3H, s; H9),
0.60 (3H, s; H10);

13C NMR (100 MHz, CDCl3):
δ = 97.4 (C4), 69.5 (C6), 69.5 (C7), 47.5 (C2), 45.5 (C1),
40.8 (C3), 29.2 (C8), 22.1 (C9), 21.7 (C10), 19.8 (C5);

HRMS (ESI) calc. for C10H19O3+ [M+H]+ 187.1329, found 187.1321.